Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
The instant application having Application No. 18/123,382 filed on March 20, 2023 is presented for examination by the examiner.
The submission of February 24, 2026 in response to the office action mailed December 10, 2025 contains no new claim set. Thus, the amended claims submitted November 24, 2025 in response to the office action mailed September 24, 2025 remain under examination. Claims 1-2, 4-14 and 16-20 are pending. Claims 3 and 15 are cancelled.
Examiner Notes
Examiner cites particular columns and line numbers in the references as applied to the claims below for the convenience of the applicant. Although the specified citations are representative of the teachings in the art and are applied to the specific limitations within the individual claim, other passages and figures may apply as well. It is respectfully requested that, in preparing responses, the applicant fully consider the references in entirety as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or disclosed by the examiner.
Information Disclosure Statement
As required by M.P.E.P. 609, the applicant’s submission of the Information Disclosure Statement dated March 11, 2026 is acknowledged by the examiner and the cited references have been considered in the examination of the claims now pending.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 4-5 and 7-10 are rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Zheng et al. CN 110426850 A (hereafter Zheng, where reference will be made to the attached machine translation).
Regarding claim 1, Calafiore teaches “A diffraction grating structure (waveguide 600, see elements thereof below), comprising:
a waveguide sheet (substrate 602 of the waveguide 600) having a first end (portion where light from light source 604 enters the waveguide) and a second end (portion with grating line 618), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 6); …
a couple-out grating (An array of diffraction grating lines 618 paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. This also includes the ridges 312, 412 and 612. That the applicant was fully informed that 612 was being construed as part of the couple-out grating is self-evident from the arguments from the second to last paragraph of page 8 of 11 through the second paragraph of page 9 of 11 of the applicant’s remarks filed November 24, 2025. That 612 itself would be considered to be a grating is evident as follows. In paragraph [0031] Calafiore states: “The ridges 312 run parallel to one another in a plane parallel to the plane of the substrate 302 (perpendicular to the plane of FIGS. 3A and 3B) and have triangular cross-sections formed by first 321 and second 322 sides. Such a configuration is sometimes referred to as a blazed grating configuration.” As evidenced by Luo, a blazed structure of transparent material acts as a diffraction grating, even absent a coating layer thereon (see 1008 and 1012 in Fig. 10A and descriptions thereof). Furthermore, if the grating lines of Calafiore did not rest on a blazed structure, but rather were a continuous flat film, the device of Calafiore would not diffract light. Furthermore, an array of triangularly shaped ridges of an undisclosed transparent material with periods of 300 to 500 nm is a grating in the instant application, thus, this same structure in Calafiore with periods of 150 nm to 600 nm (paragraph [0046]) is also a diffraction grating. Lastly, Calafiore does not actually explicitly discuss the diffraction occurring due to any of the particular elements, thus the silence of Calafiore as to diffraction explicitly occurring due to the ridges cannot be taken as evidence that diffraction is not occurring. Rather, an ordinary skilled artisan would be sufficiently familiar with diffractive in-coupling and out-coupling elements in head-mounted displays to known that when an outcoupler is discloses as being a diffraction grating that it therefor operates under the regime of diffraction.) disposed at the second end of the waveguide sheet (see Fig. 6) and comprising a blazed grating (see Figs. 3C, 4A or 4B); and
a functional layer (grating lines 318, 418, 618) disposed on the couple-out grating (see Figs. 3C, 4A or 4B the grating lines are disposed on the ridges 312, 412 and 612), wherein: …
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).” emphasis added) to transmit the light coupled in the waveguide sheet … to the couple-out grating (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet (ridges 612, lines 618 and overcoat layer 624 are a diffraction grating device, see paragraph [0046]. Given that this is an out-coupling diffraction grating, an ordinary skilled artisan would reasonably deduce that it operates by diffraction.) to couple the light in the waveguide sheet out to the functional layer (see light-path in 612 in Fig. 6)… and
the functional layer is configured to refract the light coupled out by the couple-out grating to an ambient environment (paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. See paragraph [0032] the grating lines 318, 418 or 618 refract light because they are a slab of transparent material, such as silicon nitride (Si.sub.3N.sub.4), silicon oxide (SiO.sub.2), silicon oxynitride, siliconoxycarbonitride, a metal oxide, etc. where the refractive index of the array of grating lines 318 is different from the refractive index of the array of ridges 312.) and increase a light-outcoupling rate of the couple-out grating (Because the structure of the claimed system, as identified above is the same as that claimed, it must inherently perform the same function and increase a light-outcoupling rate of the couple-out grating. See MPEP §2114(I)) “If an examiner concludes that a functional limitation is an inherent characteristic of the prior art, then to establish a prima case of anticipation or obviousness, the examiner should explain that the prior art structure inherently possesses the functionally defined limitations of the claimed apparatus. In re Schreiber, 128 F.3d at 1478, 44 USPQ2d at 1432. See also Bettcher Industries, Inc. v. Bunzl USA, Inc., 661 F.3d 629, 639-40,100 USPQ2d 1433, 1440 (Fed. Cir. 2011).” In the instant case, the functional layer may be TiO2, one of the two preferred choices in the instant application, see claim 4, thus it will perform the same function);
wherein the functional layer is disposed on only the couple-out grating (Calafiore only discloses a couple-out grating and thus only discloses a functional layer on the couple-out grating) and covers all light couple-out surfaces of the couple-out grating (the functional layer 318, 418 or 618 covers each of the first sides 321, 421 and thus “all light couple-out surfaces” because light is only out-coupled from the waveguide toward the user via the angled first sides, not the second sides 322, 422. See e.g. out-coupling of the display light 655 in Fig. 6, paragraph [0046]);
the functional layer comprises a high refractive index film layer (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5); a refractive index of the functional layer is greater than or equal to 1.8 (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a refractive index of equal to or greater than 1.8 because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5).”
However, Calafiore fails to explicitly teach “a couple-in grating disposed at the first end of the waveguide sheet and comprising a tilted grating; … the couple-in grating is configured to couple light in the waveguide sheet;… the waveguide sheet is configured to transmit the light coupled in the waveguide sheet by the couple-in grating.”
Chen teaches “A diffraction grating structure (Figs. 1, 3, 4, 5 or 7), comprising:
a waveguide sheet (lens body 10, waveguide 101, and/or waveguide 102, and/or waveguide 103) having a first end (the end with coupling-in region 11) and a second end (the end with coupling-out area 13), the first end and the second end being two opposite ends of the waveguide sheet (see Figs. 1, 3-5 or 7);
a couple-in grating (11 see paragraph [0050]: “incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure.”) disposed at the first end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a tilted grating (tilted grating 61);
a couple-out grating (13 see paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) disposed at the second end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a … grating (grating 61 or 62); and
… wherein:
the couple-in grating is configured to couple light in the waveguide sheet (paragraph [0050]: “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”);
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”) to transmit the light coupled in the waveguide sheet by the couple-in grating to the couple-out grating (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet ((paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) to couple the light in the waveguide sheet out to … an ambient environment (paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13. After being diffracted by the nanostructure, the light is output to the human eye.”).”
Chen further teaches (paragraph [0050]): “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to introduce a couple-in grating as taught by Chen into the display structure of Calafiore for the purpose of introducing the incident light at an angle that exhibits total internal reflection in the waveguide as taught by Chen thereby enabling the light to travel within the waveguide as designed.
However, Calafiore fails to teach “the couple-out grating is protruding from the waveguide sheet or has a direct contact surface with the waveguide sheet.” Note however, that Calafiore teaches grating structures in Fig. 3C and Fig. 4B that protrude from the waveguide sheet with no overcoat layer thereon, however, it is ambiguous whether Figs. 3C and 4B represent only intermediate products or if they are also examples of a final configuration because paragraph [0035] states “Turning to FIG. 3D, the array of grating lines 318 may be over-coated with an overcoat layer 324 of material having a refractive index different from the material of the grating lines 318.” (emphasis added) and it is not clear whether the use of the verb “may” means that Calafiore also intends Fig. 3C to be a possible final product or if “may” is referring to the two options of the refractive index of the over-coat layer.
Lutolf teaches a waveguide-based display with incoupler gratings 100 and outcoupler gratings 102 that can be either arranged protruding out from the waveguide sheet as shown in Fig. 10a, 10b and 10d (for the outcoupling grating) or can be embedded into the optical substrate as shown in Fig. 10c.
Thus Calafiore discloses the claimed invention except that an embedded grating is used instead of a surface grating. Lutolf shows that a surface grating protruding out from the waveguide sheet is an equivalent structure in the art. Therefore, because these two out-coupling gratings were art-recognized equivalents before the effective filing date of the claimed invention, one of ordinary skill in the art would have found it obvious to substitute a surface grating for an embedded grating, and the results thereof would have been predictable. See MPEP §2144.06 and 2143 (I)(B).
However Calafiore and Chen fail to teach “and a thickness of the functional layer ranges from 20 nm to 150 nm.”
Note that Calafiore does teach “the refractive indices of the grating lines 202 and the substrate 204, the tilt angle α, the thickness t, and/or the duty cycle k of the grating lines 202 may be selected to reduce or suppress the rainbow effect” (paragraph [0027]).
Zheng teaches a coated diffraction grating for a waveguide-based display. Zheng further teaches “wherein when the functional layer comprises a high refractive index film layer (paragraph [0011]: “the material of the high refractive index film layer”), and a thickness of the functional layer ranges from 20 nm to 150 nm (paragraph [0011]: “The thickness of the high refractive index film layer is 5nm to 150nm”).”
Zheng further teaches (paragraph [0007]): “the present invention aims to propose a single-layer full-color coupled waveguide display grating coupler, which should have the performance of achieving high efficiency coupling of a single-layer waveguide grating in a wider visible spectrum range. To this end, the technical solution adopted by the present invention is a single-layer full-color coupled waveguide display grating coupler, including: a waveguide, i.e. a transparent substrate, a grating layer of the same material or with a similar refractive index as the transparent substrate layer, a high refractive index material film layer on the grating layer, and a metal film layer on the high refractive index material. The morphology, period, groove depth, groove top angle, material of the grating layer, the thickness and refractive index of the high refractive index layer, and the thickness and refractive index of the metal film layer make the grating have a high first-order diffraction efficiency of more than 70% in the visible light spectrum range of 450nm-700nm.”
Thus the Calafiore combination discloses the claimed invention except for the thickness of the titanium oxide layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the thickness of the titanium oxide layer to be 20 nm to 150 nm within the range of 5 to 150 nm taught by Zheng, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the thickness of the high refractive index layer is an art recognized results effective variable in that it impacts the first-order diffraction efficiency for visible light as taught by Zheng paragraph [0007] and can be selected to reduce or suppress the rainbow effect as taught by Calafiore (paragraph [0027]. Thus one would have been motivated to optimize the thickness of the titanium oxide layer because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because Calafiore is silent regarding the particular choice of the thickness of the grating lines.
Regarding claim 4, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 1,” and Calafiore further teaches “wherein the functional layer comprises a titanium oxide film layer (paragraph [0028]: “a layer of grating material such as … TiO2”) or a zirconium oxide film layer (this choice is optional).”
Regarding claim 5, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 4,” and Calafiore further teaches “wherein the functional layer comprises the titanium oxide film layer (paragraph [0028]: “a layer of grating material such as … TiO2”),” however, Calafiore fails to explicitly teach “and the thickness of the functional layer is 90 nm.”
Note that Calafiore does teach “the refractive indices of the grating lines 202 and the substrate 204, the tilt angle α, the thickness t, and/or the duty cycle k of the grating lines 202 may be selected to reduce or suppress the rainbow effect” (paragraph [0027]).
Zheng teaches a coated diffraction grating for a waveguide-based display. Zheng further teaches “wherein the functional layer comprises the titanium oxide film layer (paragraph [0011]: “the material of the high refractive index film layer”), and the thickness of the functional layer is 90 nm (paragraph [0011]: “The thickness of the high refractive index film layer is 5nm to 150nm”).”
Zheng further teaches (paragraph [0007]): “the present invention aims to propose a single-layer full-color coupled waveguide display grating coupler, which should have the performance of achieving high efficiency coupling of a single-layer waveguide grating in a wider visible spectrum range. To this end, the technical solution adopted by the present invention is a single-layer full-color coupled waveguide display grating coupler, including: a waveguide, i.e. a transparent substrate, a grating layer of the same material or with a similar refractive index as the transparent substrate layer, a high refractive index material film layer on the grating layer, and a metal film layer on the high refractive index material. The morphology, period, groove depth, groove top angle, material of the grating layer, the thickness and refractive index of the high refractive index layer, and the thickness and refractive index of the metal film layer make the grating have a high first-order diffraction efficiency of more than 70% in the visible light spectrum range of 450nm-700nm.”
Thus the Calafiore – Chen - Zheng combination introduced for claim 1 discloses the claimed invention except for the thickness of the titanium oxide layer being 90 nm. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the thickness of the titanium oxide layer to be 90 nm, within the range of 5 to 150 nm taught by Zheng, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the thickness of the high refractive index layer is an art recognized results effective variable in that it impacts the first-order diffraction efficiency for visible light as taught by Zheng paragraph [0007] and can be selected to reduce or suppress the rainbow effect as taught by Calafiore (paragraph [0027]. Thus one would have been motivated to optimize the thickness of the titanium oxide layer because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because Calafiore is silent regarding the particular choice of the thickness of the grating lines.
Regarding claim 7, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 1,” however, Calafiore fails to teach “comprising three layers of waveguide sheets, wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively; and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively.”
Chen teaches (Fig. 7) “comprising three layers of waveguide sheets (paragraph [0054]: “three layers of holographic diffraction waveguide lenses”), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively (paragraph [0054]: “Among them, the functional areas of the three holographic diffraction waveguide lenses are composed of nano-diffraction gratings.” although not explicitly shown in Fig. 7, an ordinary skilled artisan would reasonably deduce that each of the waveguides contains a couple-in grating and a couple-out grating at the two ends thereof, as is true of Figs. 1-3, 5 and 6); and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively (paragraph [0054]: “The first diffractive waveguide lens 101, the second diffractive waveguide lens 102 and the third diffractive waveguide lens 103 are closely attached to each other in vertical space and are used to transmit red, green and blue image lights respectively… The period, height, duty cycle and other parameters of the nano-diffraction gratings corresponding to different lenses are different, and different lenses only couple and transmit one color image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen – Zheng combination to have three waveguides one for each of red, green and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0054]).
Regarding claim 8, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 7,” however, Calafiore does not explicitly teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Chen teaches “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (see Figs. 2, 5 or 6); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (this choice is optional).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the couple-in grating and the couple-out grating to be disposed on a same side of the waveguide sheet as taught by Chen, because Calafiore does not specify the location of the couple-in grating, and Chen teaches that having both gratings on the same side of the waveguide is an appropriate choice.
Regarding claim 9, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 1,” however Calafiore is silent regarding “comprising two layers of waveguide sheets, wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively;
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light; and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light.”
Chen teaches (Figs. 4-6) “comprising two layers of waveguide sheets (a first diffractive waveguide lens 101 and a second diffractive waveguide lens 102), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively (see Figs. 5 and 6);
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light (paragraph [0052]: “the single-channel diffraction waveguide lens is used to couple the green image light”); and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light (paragraph [0052]: “The dual-channel diffraction waveguide lens is used to couple the image light of other colors. Preferably, the dual-channel diffraction waveguide lens is used to couple the blue image light and the red image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen -Zheng combination to have two waveguides one for green light and one for red and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0052]).
Regarding claim 10, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 9,” however, Calafiore does not explicitly teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Chen teaches “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (see Figs. 2, 5 or 6); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (this choice is optional).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the couple-in grating and the couple-out grating to be disposed on a same side of the waveguide sheet as taught by Chen, because Calafiore does not specify the location of the couple-in grating, and Chen teaches that having both gratings on the same side of the waveguide is an appropriate choice.
Claims 1, 4-10 are rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation) and Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf).
Regarding claim 1, Calafiore teaches “A diffraction grating structure (waveguide 600, see elements thereof below), comprising:
a waveguide sheet (substrate 602 of the waveguide 600) having a first end (portion where light from light source 604 enters the waveguide) and a second end (portion with grating line 618), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 6); …
a couple-out grating (An array of diffraction grating lines 618 paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. This also includes the ridges 312, 412 and 612. That the applicant was fully informed that 612 was being construed as part of the couple-out grating is self-evident from the arguments from the second to last paragraph of page 8 of 11 through the second paragraph of page 9 of 11 of the applicant’s remarks filed November 24, 2025. That 612 itself would be considered to be a grating is evident as follows. In paragraph [0031] Calafiore states: “The ridges 312 run parallel to one another in a plane parallel to the plane of the substrate 302 (perpendicular to the plane of FIGS. 3A and 3B) and have triangular cross-sections formed by first 321 and second 322 sides. Such a configuration is sometimes referred to as a blazed grating configuration.” As evidenced by Luo, a blazed structure of transparent material acts as a diffraction grating, even absent a coating layer thereon (see 1008 and 1012 in Fig. 10A and descriptions thereof). Furthermore, if the grating lines of Calafiore did not rest on a blazed structure, but rather were a continuous flat film, the device of Calafiore would not diffract light. Furthermore, an array of triangularly shaped ridges of an undisclosed transparent material with periods of 300 to 500 nm is a grating in the instant application, thus, this same structure in Calafiore with periods of 150 nm to 600 nm (paragraph [0046]) is also a diffraction grating. Lastly, Calafiore does not actually explicitly discuss the diffraction occurring due to any of the particular elements, thus the silence of Calafiore as to diffraction explicitly occurring due to the ridges cannot be taken as evidence that diffraction is not occurring. Rather, an ordinary skilled artisan would be sufficiently familiar with diffractive in-coupling and out-coupling elements in head-mounted displays to known that when an outcoupler is discloses as being a diffraction grating that it therefor operates under the regime of diffraction.) disposed at the second end of the waveguide sheet (see Fig. 6) and comprising a blazed grating (see Figs. 3C, 4A or 4B); and
a functional layer (grating lines 318, 418, 618) disposed on the couple-out grating (see Figs. 3C, 4A or 4B, 318, 418, 618 are disposed on the ridges 312, 412 and 612), wherein: …
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).” emphasis added) to transmit the light coupled in the waveguide sheet … to the couple-out grating (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet (ridges 612, lines 618 and overcoat layer 624 are a diffraction grating device, see paragraph [0046]. Given that this is an out-coupling diffraction grating, an ordinary skilled artisan would reasonably deduce that it operates by diffraction.) to couple the light in the waveguide sheet out to the functional layer (see light-path in 612 in Fig. 6)… and
the functional layer is configured to refract the light coupled out by the couple-out grating to an ambient environment (paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. See paragraph [0032] the grating lines 318, 418 or 618 refract light because they are a slab of transparent material, such as silicon nitride (Si.sub.3N.sub.4), silicon oxide (SiO.sub.2), silicon oxynitride, siliconoxycarbonitride, a metal oxide, etc. where the refractive index of the array of grating lines 318 is different from the refractive index of the array of ridges 312.) and increase a light-outcoupling rate of the couple-out grating (Because the structure of the claimed system, as identified above is the same as that claimed, it must inherently perform the same function and increase a light-outcoupling rate of the couple-out grating. See MPEP §2114(I)) “If an examiner concludes that a functional limitation is an inherent characteristic of the prior art, then to establish a prima case of anticipation or obviousness, the examiner should explain that the prior art structure inherently possesses the functionally defined limitations of the claimed apparatus. In re Schreiber, 128 F.3d at 1478, 44 USPQ2d at 1432. See also Bettcher Industries, Inc. v. Bunzl USA, Inc., 661 F.3d 629, 639-40,100 USPQ2d 1433, 1440 (Fed. Cir. 2011).” In the instant case, the functional layer may be TiO2, one of the two preferred choices in the instant application, see claim 4, thus it will perform the same function);
wherein the functional layer is disposed on only the couple-out grating (Calafiore only discloses a couple-out grating and thus only discloses a functional layer on the couple-out grating) and covers all light couple-out surfaces of the couple-out grating (the functional layer 318, 418 or 618 covers each of the first sides 321, 421 and thus “all light couple-out surfaces” because light is only out-coupled from the waveguide toward the user via the angled first sides, not the second sides 322, 422. See e.g. out-coupling of the display light 655 in Fig. 6, paragraph [0046]);
the functional layer comprises a high refractive index film layer (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5); a refractive index of the functional layer is greater than or equal to 1.8 (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a refractive index of equal to or greater than 1.8 because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5).”
However, Calafiore fails to explicitly teach “a couple-in grating disposed at the first end of the waveguide sheet and comprising a tilted grating; … the couple-in grating is configured to couple light in the waveguide sheet;… the waveguide sheet is configured to … transmit the light coupled in the waveguide sheet by the couple-in grating.”
Chen teaches “A diffraction grating structure (Figs. 1, 3, 4, 5 or 7), comprising:
a waveguide sheet (lens body 10, waveguide 101, and/or waveguide 102, and/or waveguide 103) having a first end (the end with coupling-in region 11) and a second end (the end with coupling-out area 13), the first end and the second end being two opposite ends of the waveguide sheet (see Figs. 1, 3-5 or 7);
a couple-in grating (11 see paragraph [0050]: “incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure.”) disposed at the first end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a tilted grating (tilted grating 61);
a couple-out grating (13 see paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) disposed at the second end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a … grating (grating 61 or 62); and
… wherein:
the couple-in grating is configured to couple light in the waveguide sheet (paragraph [0050]: “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”);
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”) to transmit the light coupled in the waveguide sheet by the couple-in grating to the couple-out grating (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet ((paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) to couple the light in the waveguide sheet out to … an ambient environment (paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13. After being diffracted by the nanostructure, the light is output to the human eye.”).”
Chen further teaches (paragraph [0050]): “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to introduce a couple-in grating as taught by Chen into the display structure of Calafiore for the purpose of introducing the incident light at an angle that exhibits total internal reflection in the waveguide as taught by Chen thereby enabling the light to travel within the waveguide as designed.
However, Calafiore fails to teach “the couple-out grating is protruding from the waveguide sheet or has a direct contact surface with the waveguide sheet.” Note however, that Calafiore teaches grating structures in Fig. 3C and Fig. 4B that protrude from the waveguide sheet with no overcoat layer thereon, however, it is ambiguous whether Figs. 3C and 4B represent only intermediate products or if they are also examples of a final configuration because paragraph [0035] states “Turning to FIG. 3D, the array of grating lines 318 may be over-coated with an overcoat layer 324 of material having a refractive index different from the material of the grating lines 318.” (emphasis added) and it is not clear whether the use of the verb “may” means that Calafiore also intends Fig. 3C to be a possible final product or if “may” is referring to the two options of the refractive index of the over-coat layer.
Lutolf teaches a waveguide-based display with incoupler gratings 100 and outcoupler gratings 102 that can be either arranged protruding out from the waveguide sheet as shown in Fig. 10a, 10b and 10d (for the outcoupling grating) or can be embedded into the optical substrate as shown in Fig. 10c.
Thus Calafiore discloses the claimed invention except that an embedded grating is used instead of a surface grating. Lutolf shows that a surface grating protruding out from the waveguide sheet is an equivalent structure in the art. Therefore, because these two out-coupling gratings were art-recognized equivalents before the effective filing date of the claimed invention, one of ordinary skill in the art would have found it obvious to substitute a surface grating for an embedded grating, and the results thereof would have been predictable. See MPEP §2144.06 and 2143 (I)(B).
However Calafiore and Chen fail to teach “and a thickness of the functional layer ranges from 20 nm to 150 nm.”
Note that Calafiore does teach “the refractive indices of the grating lines 202 and the substrate 204, the tilt angle α, the thickness t, and/or the duty cycle k of the grating lines 202 may be selected to reduce or suppress the rainbow effect” (paragraph [0027]).
Lutolf teaches a waveguide-based display with coated grating structures where “the functional layer comprises a high refractive index film layer (paragraph [0028]: “The materials of the dielectric coating of the grating coupler are chosen among materials having an index of refraction higher than 1.4 for wavelengths between 0.2 μm and 2 μm. Preferably the dielectric coating materials are chosen among: … TiO2… ZrO2”); a refractive index of the functional layer is greater than or equal to 1.8 (paragraph [0028]: “the dielectric coating materials are chosen among: … TiO2… ZrO2”. Given that titanium oxide and zirconium oxide are both one of the preferred materials of the high refractive index film layer, Lutolf’s choice of TiO2 or ZrO2 also has the property of a refractive index of equal to or greater than 1.8 because it is the same material as that disclosed in the instant application, see e.g. claims 4-6); and a thickness of the functional layer ranges from 20 nm to 150 nm (paragraphs [0123-0136]: the period P of the diffraction grating elements 4; the ridge width s; … the sidewall coating thickness ds; the thickness of the dielectric coating dt, this dielectric coating being arranged to the side of the incident light beam 10” Table 1 P is 190 nm to 1000 nm; s is 0.25 to 0.7 x P; ds is 5 nm to (P − 0.8s); dt is 5 nm to 0.5P. For example, this would include P=330 nm; s = 2P/3 = 220 nm; dt = P/3 = 110 nm; ds = P – s = 330 – 220 = 110 nm, such that both the thickness of the dielectric coating on the sides of the grating and on the tops of the grating are 110 nm thick. This would also include P=270 nm; s = 2P/3 = 180 nm; dt = P/3 = 90 nm; ds = P – s = 270 – 180 = 90 nm, such that both the thickness of the dielectric coating on the sides of the grating and on the tops of the grating are 90 nm thick).”
Lutolf further teaches (paragraph [0028]): “The materials of the dielectric coating of the grating coupler are chosen among materials having an index of refraction higher than 1.4 for wavelengths between 0.2 μm and 2 μm. Preferably the dielectric coating materials are chosen among: … TiO2 or … ZrO2”.
Lutolf further teaches (paragraph [0123]): “In order to achieve coupling efficiencies higher than 50% in a specific positive or negative diffraction order, preferably the first diffraction order, the skilled person will be able, by using the further explained light coupling optimization method, to identify … the needed materials of the asymmetric dielectric coating 5 to be arranged on the grating elements 4 of the grating coupler 1 in order to achieve that goal.”
It is a well-established proposition that the selection of a known material based on its suitability for its intended use is within the skill of one of ordinary skill in the art Sinclair & Carroll Co. v.Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945) See also In reLeshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960) (selection of a known plastic to make a container of a type made of plastics prior to the invention was held to be obvious). MPEP §2144.07.
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose TiO2 or ZrO2 as the material for the high refractive index coating of Calafiore in addition to TiO2 as taught by Lutolf in the diffraction grating structure of the Calafiore – Chen combination because Lutolf teaches that the skilled person is able to identify the needed material of the coating (paragraph [0123]) and further since it has been held that the selection of a known material based on its suitability for its intended use is within the skill of one of ordinary skill in the art Sinclair & Carroll Co. v.Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945) See also In reLeshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960) (selection of a known plastic to make a container of a type made of plastics prior to the invention was held to be obvious). MPEP §2144.07.
Lutolf further teaches (paragraph [0123]): “In order to achieve coupling efficiencies higher than 50% in a specific positive or negative diffraction order, preferably the first diffraction order, the skilled person will be able, by using the further explained light coupling optimization method, to identify the required geometrical parameters and the needed materials of the asymmetric dielectric coating 5 to be arranged on the grating elements 4 of the grating coupler 1 in order to achieve that goal.”
The Calafiore – Chen – Lutolf combination discloses the claimed invention except for the thickness of the functional layer being 20 nm to 150 nm. It would have been obvious to one of ordinary skill in the art at the time the invention was made to choose the thickness of the coating to be 90 nm or 110 nm which is within the ranges disclosed by Lutolf because Lutolf teaches that the skilled person is able to identify the required geometrical parameters to achieve the desired coupling efficiencies (paragraph [0123]) and further since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955).
Regarding claim 4, the Calafiore – Chen - Lutolf combination teaches “The diffraction grating structure according to claim 1, wherein the functional layer comprises a titanium oxide film layer (Calafiore paragraph [0028] or Lutolf paragraph [0028]) or a zirconium oxide film layer (the modification of Calafiore in view of Lutolf introduced for claim 1 above, already modified the material of the functional layer to include the option of a zirconium oxide film layer as taught by Lutolf, paragraph [0028]).”
Regarding claim 5, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 4,” and Calafiore further teaches “wherein the functional layer comprises the titanium oxide film layer (paragraph [0028]).” However, Calafiore fails to teach “and the thickness of the functional layer is 90 nm.”
Note that Calafiore does teach “the refractive indices of the grating lines 202 and the substrate 204, the tilt angle α, the thickness t, and/or the duty cycle k of the grating lines 202 may be selected to reduce or suppress the rainbow effect” (paragraph [0027]).
Lutolf teaches a waveguide-based display with coated grating structures where “wherein the functional layer comprises the titanium oxide film layer (paragraph [0028]: “The materials of the dielectric coating of the grating coupler are chosen among materials having an index of refraction higher than 1.4 for wavelengths between 0.2 μm and 2 μm. Preferably the dielectric coating materials are chosen among: … TiO2”), and the thickness of the functional layer is 90 nm (paragraphs [0123-0136]: the period P of the diffraction grating elements 4; the ridge width s; … the sidewall coating thickness ds; the thickness of the dielectric coating dt, this dielectric coating being arranged to the side of the incident light beam 10” Table 1 P is 190 nm to 1000 nm; s is 0.25 to 0.7 x P; ds is 5 nm to (P − 0.8s); dt is 5 nm to 0.5P. For example, this would include P=270 nm; s = 2P/3 = 180 nm; dt = P/3 = 90 nm; ds = P – s = 270 – 180 = 90 nm, such that both the thickness of the dielectric coating on the sides of the grating and on the tops of the grating are 90 nm thick).”
Lutolf further teaches (paragraph [0123]): “In order to achieve coupling efficiencies higher than 50% in a specific positive or negative diffraction order, preferably the first diffraction order, the skilled person will be able, by using the further explained light coupling optimization method, to identify the required geometrical parameters and the needed materials of the asymmetric dielectric coating 5 to be arranged on the grating elements 4 of the grating coupler 1 in order to achieve that goal.”
The Calafiore – Chen – Lutolf combination introduced for claim 1 discloses the claimed invention except for the thickness of the titanium oxide layer being 90 nm. It would have been obvious to one of ordinary skill in the art at the time the invention was made to choose the thickness of the coating to be 90 nm which is within the ranges disclosed by Lutolf because Lutolf teaches that the skilled person is able to identify the required geometrical parameters to achieve the desired coupling efficiencies (paragraph [0123]) and further since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955).
Regarding claim 6, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 4,” however, Calafiore fails to teach “wherein the functional layer comprises the zirconium oxide film layer, and the thickness of the functional layer is 110 nm.”
Note however that Calafiore does teach zirconium oxide as a high refractive index material that can be used in the construction of the diffraction grating see paragraph [0035].
Lutolf teaches a waveguide-based display with coated grating structures where “wherein the functional layer comprises the zirconium oxide film layer (paragraph [0028]: “The materials of the dielectric coating of the grating coupler are chosen among materials having an index of refraction higher than 1.4 for wavelengths between 0.2 μm and 2 μm. Preferably the dielectric coating materials are chosen among: … ZrO2”), and the thickness of the functional layer is 110 nm (paragraphs [0123-0136]: the period P of the diffraction grating elements 4; the ridge width s; … the sidewall coating thickness ds; the thickness of the dielectric coating dt, this dielectric coating being arranged to the side of the incident light beam 10” Table 1 P is 190 nm to 1000 nm; s is 0.25 to 0.7 x P; ds is 5 nm to (P − 0.8s); dt is 5 nm to 0.5P. For example, this would include P=330 nm; s = 2P/3 = 220 nm; dt = P/3 = 110 nm; ds = P – s = 330 – 220 = 110 nm, such that both the thickness of the dielectric coating on the sides of the grating and on the tops of the grating are 110 nm thick).”
Lutolf further teaches (paragraph [0028]): “The materials of the dielectric coating of the grating coupler are chosen among materials having an index of refraction higher than 1.4 for wavelengths between 0.2 μm and 2 μm. Preferably the dielectric coating materials are chosen among: … TiO2 or … ZrO2”.
Lutolf further teaches (paragraph [0123]): “In order to achieve coupling efficiencies higher than 50% in a specific positive or negative diffraction order, preferably the first diffraction order, the skilled person will be able, by using the further explained light coupling optimization method, to identify … the needed materials of the asymmetric dielectric coating 5 to be arranged on the grating elements 4 of the grating coupler 1 in order to achieve that goal.”
It is a well-established proposition that the selection of a known material based on its suitability for its intended use is within the skill of one of ordinary skill in the art Sinclair & Carroll Co. v.Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945) See also In reLeshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960) (selection of a known plastic to make a container of a type made of plastics prior to the invention was held to be obvious). MPEP §2144.07.
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose ZrO2 as the material for the high refractive index coating of Calafiore instead of TiO2 as taught by Lutolf in the diffraction grating structure of the Calafiore – Chen combination because Lutolf teaches that the skilled person is able to identify the needed material of the coating (paragraph [0123]) and further since it has been held that the selection of a known material based on its suitability for its intended use is within the skill of one of ordinary skill in the art Sinclair & Carroll Co. v.Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945) See also In reLeshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960) (selection of a known plastic to make a container of a type made of plastics prior to the invention was held to be obvious). MPEP §2144.07.
Lutolf further teaches (paragraph [0123]): “In order to achieve coupling efficiencies higher than 50% in a specific positive or negative diffraction order, preferably the first diffraction order, the skilled person will be able, by using the further explained light coupling optimization method, to identify the required geometrical parameters and the needed materials of the asymmetric dielectric coating 5 to be arranged on the grating elements 4 of the grating coupler 1 in order to achieve that goal.”
The Calafiore – Chen – Lutolf combination discloses the claimed invention except for the thickness of the zirconium oxide layer being 110 nm. It would have been obvious to one of ordinary skill in the art at the time the invention was made to choose the thickness of the coating to be 110 nm which is within the ranges disclosed by Lutolf because Lutolf teaches that the skilled person is able to identify the required geometrical parameters to achieve the desired coupling efficiencies (paragraph [0123]) and further since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955).
Regarding claim 7, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 1,” however, Calafiore fails to teach “comprising three layers of waveguide sheets, wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively; and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively.”
Chen teaches (Fig. 7) “comprising three layers of waveguide sheets (paragraph [0054]: “three layers of holographic diffraction waveguide lenses”), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively (paragraph [0054]: “Among them, the functional areas of the three holographic diffraction waveguide lenses are composed of nano-diffraction gratings.” although not explicitly shown in Fig. 7, an ordinary skilled artisan would reasonably deduce that each of the waveguides contains a couple-in grating and a couple-out grating at the two ends thereof, as is true of Figs. 1-3, 5 and 6); and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively (paragraph [0054]: “The first diffractive waveguide lens 101, the second diffractive waveguide lens 102 and the third diffractive waveguide lens 103 are closely attached to each other in vertical space and are used to transmit red, green and blue image lights respectively… The period, height, duty cycle and other parameters of the nano-diffraction gratings corresponding to different lenses are different, and different lenses only couple and transmit one color image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen – Lutolf combination to have three waveguides one for each of red, green and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0054]).
Regarding claim 8, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 7,” however, Calafiore does not explicitly teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Chen teaches “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (see Figs. 2, 5 or 6); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (this choice is optional).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the couple-in grating and the couple-out grating to be disposed on a same side of the waveguide sheet as taught by Chen, because Calafiore does not specify the location of the couple-in grating, and Chen teaches that having both gratings on the same side of the waveguide is an appropriate choice.
Regarding claim 9, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 1,” however Calafiore is silent regarding “comprising two layers of waveguide sheets, wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively;
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light; and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light.”
Chen teaches (Figs. 4-6) “comprising two layers of waveguide sheets (a first diffractive waveguide lens 101 and a second diffractive waveguide lens 102), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively (see Figs. 5 and 6);
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light (paragraph [0052]: “the single-channel diffraction waveguide lens is used to couple the green image light”); and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light (paragraph [0052]: “The dual-channel diffraction waveguide lens is used to couple the image light of other colors. Preferably, the dual-channel diffraction waveguide lens is used to couple the blue image light and the red image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen – Lutolf combination to have two waveguides one for green light and one for red and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0052]).
Regarding claim 10, the Calafiore – Chen - Lutolf combination teaches “The diffraction grating structure according to claim 9,” however, Calafiore does not explicitly teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Chen teaches “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (see Figs. 2, 5 or 6); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (this choice is optional).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the couple-in grating and the couple-out grating to be disposed on a same side of the waveguide sheet as taught by Chen, because Calafiore does not specify the location of the couple-in grating, and Chen teaches that having both gratings on the same side of the waveguide is an appropriate choice.
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Zheng et al. CN 110426850 A (hereafter Zheng, where reference will be made to the attached machine translation) as applied to claim 1 above, and further in view of Luo et al. US 2021/0033867 A1 (hereafter Luo).
Regarding claim 2, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 1,” However Calafiore, Chen, Lutolf and Zheng fail to explicitly teach “wherein:
a period of the couple-out grating ranges from 300 nm to 500 nm; and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees; and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees.”
Note that Calafiore does teach a period of the couple-out grating ranges from 150 nm to 600 nm (paragraph [0046]) and a blaze angle of the couple-out grating ranges from 30 to 60 degrees (paragraph [0046]). Furthermore, Calafiore teaches (paragraph [0024]): “At least one of pitch, duty cycle, height, slant angle, or refractive index of the array of grating lines is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light” where it should be noted that by the geometry of triangles, the anti-blaze angle contributes to the duty cycle, height and pitch of the grating lines for a given slant angle However, these disclosed ranges are too wide to be considered as anticipating the claimed ranges.
Luo teaches an augmented reality display, including a waveguide 1004, a grating 1008 configured to diffract light having a wavelength in the visible spectrum such that the light incident thereon is guided within the waveguide 1004 by TIR, and a blazed out-coupling grating 1012 (see Fig. 10A and paragraph [0110].
Luo further teaches “wherein:
a period of the couple-out grating ranges from 300 nm to 500 nm (paragraph [0129]: “The diffraction gratings 1008 may have a pitch of … 300 nm to 400 nm, 250 nm to 450 nm, or a pitch in any range defined by any of these values, according to various embodiments.”); and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees (paragraph [0130]: “The diffraction gratings 1008 may have blaze angles of about 10 to 70 degrees… or any value in a range defined by these values”); and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees (paragraph [0130]: “anti-blaze angles (steep side) of 140 to 70 degrees or any value in a range defined by these values”).”
It has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I).
In the current instance Calafiore discloses a range of pitches between 150 nm and 600 nm which encompasses the narrower claimed range of 300 nm to 500 nm. Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose a value of the pitch within the narrower claimed range as taught by Luo, because it has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I). Note that, in the current instance, the pitch is an art recognized results effective variable in that the pitch is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024]). Thus one would have been motivated to optimize the pitch because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that pitches between 300 and 450 nm are appropriate.
It has been held that in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). See MPEP §2144.05(I) first paragraph.
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose the blaze angle of 5 to 40 degrees, which overlaps the disclosed range in Calafiore of 30 to 60 degrees as taught by Luo who discloses a blaze angle of 10 to 30 degrees, since it has been held that in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). See MPEP §2144.05(I) first paragraph. In the current instance, the slant angle is an art recognized results effective variable in that it is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024]). Thus one would have been motivated to optimize the blaze angle because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that blaze angles of 10 to 30 degrees are appropriate.
Lastly, the Calafiore – Chen – Zheng combination discloses the claimed invention except for an anti-blaze angle of 50 degrees to 85 degrees. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose an anti-blaze angle of 50 degrees to 85 degrees which overlaps the range of 70 to 140 degrees taught by Luo, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the slant angle is an art recognized results effective variable in that it is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024], by the geometry of triangles, the anti-blaze angle contributes to the duty cycle, height and pitch of the grating lines for a given slant angle). Thus one would have been motivated to optimize the anti-blaze angle because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that anti-blaze angles of 70 to 85 degrees are appropriate.
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation) and Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) as applied to claim 1 above, and further in view of Luo et al. US 2021/0033867 A1 (hereafter Luo).
Regarding claim 2, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 1,” However Calafiore, Chen and Lutolf fail to explicitly teach “wherein:
a period of the couple-out grating ranges from 300 nm to 500 nm; and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees; and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees.”
Note that Calafiore does teach a period of the couple-out grating ranges from 150 nm to 600 nm (paragraph [0046]) and a blaze angle of the couple-out grating ranges from 30 to 60 degrees (paragraph [0046]). Furthermore, Calafiore teaches (paragraph [0024]): “At least one of pitch, duty cycle, height, slant angle, or refractive index of the array of grating lines is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light” where it should be noted that by the geometry of triangles, the anti-blaze angle contributes to the duty cycle, height and pitch of the grating lines for a given slant angle However, these disclosed ranges are too wide to be considered as anticipating the claimed ranges.
Luo teaches an augmented reality display, including a waveguide 1004, a grating 1008 configured to diffract light having a wavelength in the visible spectrum such that the light incident thereon is guided within the waveguide 1004 by TIR, and a blazed out-coupling grating 1012 (see Fig. 10A and paragraph [0110].
Luo further teaches “wherein:
a period of the couple-out grating ranges from 300 nm to 500 nm (paragraph [0129]: “The diffraction gratings 1008 may have a pitch of … 300 nm to 400 nm, 250 nm to 450 nm, or a pitch in any range defined by any of these values, according to various embodiments.”); and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees (paragraph [0130]: “The diffraction gratings 1008 may have blaze angles of about 10 to 70 degrees… or any value in a range defined by these values”); and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees (paragraph [0130]: “anti-blaze angles (steep side) of 140 to 70 degrees or any value in a range defined by these values”).”
It has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I).
In the current instance Calafiore discloses a range of pitches between 150 nm and 600 nm which encompasses the narrower claimed range of 300 nm to 500 nm. Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose a value of the pitch within the narrower claimed range as taught by Luo, because it has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I). Note that, in the current instance, the pitch is an art recognized results effective variable in that the pitch is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024]). Thus one would have been motivated to optimize the pitch because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that pitches between 300 and 450 nm are appropriate.
It has been held that in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). See MPEP §2144.05(I) first paragraph.
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose the blaze angle of 5 to 40 degrees, which overlaps the disclosed range in Calafiore of 30 to 60 degrees as taught by Luo how discloses a blaze angle of 10 to 30 degrees, since it has been held that in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). See MPEP §2144.05(I) first paragraph. In the current instance, the slant angle is an art recognized results effective variable in that it is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024]). Thus one would have been motivated to optimize the blaze angle because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that blaze angles of 10 to 30 degrees are appropriate.
Lastly, the Calafiore – Chen – Lutolf combination discloses the claimed invention except for an anti-blaze angle of 50 degrees to 85 degrees. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose an anti-blaze angle of 50 degrees to 85 degrees which overlaps the range of 70 to 140 degrees taught by Luo, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the slant angle is an art recognized results effective variable in that it is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024], by the geometry of triangles, the anti-blaze angle contributes to the duty cycle, height and pitch of the grating lines for a given slant angle). Thus one would have been motivated to optimize the anti-blaze angle because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Luo and Calafiore are directed to gratings within a waveguide-based head mounted display, where Luo teaches that anti-blaze angles of 70 to 85 degrees are appropriate.
Claims 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Zheng et al. CN 110426850 A (hereafter Zheng, where reference will be made to the attached machine translation) as applied to claim 1 above, and further in view of Singer et al. US 2020/0271847 A1 (cited in an IDS, hereafter Singer).
Regarding claim 11, the Calafiore – Chen – Lutolf – Zheng combination teaches “The diffraction grating structure according to claim 1,” and Calafiore further teaches “comprising one layer of waveguide sheet (Fig. 6 substrate 602), wherein:
the couple-in … and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively, (see Fig. 6 light is coupled-in at the upper end of 602 and the couple-out grating is at the bottom end of 602) and configured to diffract and reflect red light, green light, and blue light (e.g. paragraph [0046]: “operation with visible light” which is at least one of these colors).”
However, Calafiore fails to explicitly teach “the couple-in grating and the couple-out grating are … configured to diffract and reflect red light, green light, and blue light.”
Chen teaches “comprising one layer of waveguide sheet (Figs. 1-3) the couple-in grating and the couple-out grating are … configured to diffract and reflect red light … and blue light (paragraph [0017]: “the dual-channel diffraction waveguide lens is used to couple blue image light and red image light.”).”
Singer teaches a waveguide-based head-mounted display with input coupling gratings 26 and output coupling gratings 28, “comprising one layer of waveguide sheet (single light guide 20), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively (see Fig. 1), configured to diffract and reflect (paragraph [0072]: “the output coupling gratings 46′ can be partly transmissive and partly reflective, i.e., the output coupling gratings diffract the incident light partly in transmission and partly in reflection.”) red light, green light, and blue light (paragraph [0036]: “For the purposes of transmitting a chromatically larger spectral range, the transmitted field angle range can be reduced since chromatic effects compensate during input and output coupling or there is the option of manufacturing color multiplexing with, e.g., two or three tilted grating stacks in a light guide for the three colors of red, green and blue (RGB).” ).”
Singer further teaches (paragraph [0050]): “In the shown exemplary embodiment, the light guide arrangement 18 only has a single light guide 20, which is advantageous in view of a little complex and thin construction of the light guide arrangement 18.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to construct the waveguide-based display from a single waveguide as taught by Chen Figs. 1-3 and Singer because Singer teaches that a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]).
Chen teaches that a single waveguide can diffract and guide both red and blue light, which have the largest and smallest wavelengths, and Singer teaches that because the chromatic effects are compensated during input and output coupling a chromatically larger spectral range can be transmitted, and that such a single waveguide is an alternative to having three stacked waveguides, one for each of red, green and blue. Taken together Chen and Singer teach that one can construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light, because Singer teaches that an arrangement with a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]), and both Chen and Singer teach that a full color image having red, green and blue light is desirable.
Regarding claim 12, the Calafiore – Chen – Lutolf – Zheng – Singer combination teaches “The diffraction grating structure according to claim 11,” however, Calafiore fails to teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Singer teaches “wherein: the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (paragraph [0074]): “In FIG. 1, the input coupling gratings 26 and the output coupling gratings 28 are embedded in the light guide, light input coupling and light output coupling being implemented on opposite sides. Alternatively, input and output coupling can also be implemented on the same sides.” Emphasis added); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (paragraph [0074]): “In FIG. 1, the input coupling gratings 26 and the output coupling gratings 28 are embedded in the light guide, light input coupling and light output coupling being implemented on opposite sides.”).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to dispose the gratings either on the same side or on opposite sides of the waveguide sheet as taught by Singer in the structure of the Calafiore – Chen – Zheng – Singer combination because Singer teaches that either choice is an appropriate configuration for the couple-in and couple-out gratings (Singer paragraph [0074]).
Claims 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation) and Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) as applied to claim 1 above, and further in view of Singer et al. US 2020/0271847 A1 (cited in an IDS, hereafter Singer).
Regarding claim 11, the Calafiore – Chen – Lutolf combination teaches “The diffraction grating structure according to claim 1,” and Calafiore further teaches “comprising one layer of waveguide sheet (Fig. 6 substrate 602), wherein:
the couple-in … and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively, (see Fig. 6 light is coupled-in at the upper end of 602 and the couple-out grating is at the bottom end of 602) and configured to diffract and reflect red light, green light, and blue light (e.g. paragraph [0046]: “operation with visible light” which is at least one of these colors).”
However, Calafiore fails to explicitly teach “the couple-in grating and the couple-out grating are … configured to diffract and reflect red light, green light, and blue light.”
Chen teaches “comprising one layer of waveguide sheet (Figs. 1-3) the couple-in grating and the couple-out grating are … configured to diffract and reflect red light … and blue light (paragraph [0017]: “the dual-channel diffraction waveguide lens is used to couple blue image light and red image light.”).”
Singer teaches a waveguide-based head-mounted display with input coupling gratings 26 and output coupling gratings 28, “comprising one layer of waveguide sheet (single light guide 20), wherein:
the couple-in grating and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively (see Fig. 1), configured to diffract and reflect (paragraph [0072]: “the output coupling gratings 46′ can be partly transmissive and partly reflective, i.e., the output coupling gratings diffract the incident light partly in transmission and partly in reflection.”) red light, green light, and blue light (paragraph [0036]: “For the purposes of transmitting a chromatically larger spectral range, the transmitted field angle range can be reduced since chromatic effects compensate during input and output coupling or there is the option of manufacturing color multiplexing with, e.g., two or three tilted grating stacks in a light guide for the three colors of red, green and blue (RGB).” ).”
Singer further teaches (paragraph [0050]): “In the shown exemplary embodiment, the light guide arrangement 18 only has a single light guide 20, which is advantageous in view of a little complex and thin construction of the light guide arrangement 18.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to construct the waveguide-based display from a single waveguide as taught by Chen Figs. 1-3 and Singer because Singer teaches that a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]).
Chen teaches that a single waveguide can diffract and guide both red and blue light, which have the largest and smallest wavelengths, and Singer teaches that because the chromatic effects are compensated during input and output coupling a chromatically larger spectral range can be transmitted, and that such a single waveguide is an alternative to having three stacked waveguides, one for each of red, green and blue. Taken together Chen and Singer teach that one can construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light, because Singer teaches that an arrangement with a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]), and both Chen and Singer teach that a full color image having red, green and blue light is desirable.
Regarding claim 12, the Calafiore – Chen – Lutolf – Singer combination teaches “The diffraction grating structure according to claim 11,” however, Calafiore fails to teach “wherein:
the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet; or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet.”
Singer teaches “wherein: the couple-in grating and the couple-out grating are disposed on a same side of the waveguide sheet (paragraph [0074]): “In FIG. 1, the input coupling gratings 26 and the output coupling gratings 28 are embedded in the light guide, light input coupling and light output coupling being implemented on opposite sides. Alternatively, input and output coupling can also be implemented on the same sides.” Emphasis added); or
the couple-in grating and the couple-out grating are disposed on different sides of the waveguide sheet (paragraph [0074]): “In FIG. 1, the input coupling gratings 26 and the output coupling gratings 28 are embedded in the light guide, light input coupling and light output coupling being implemented on opposite sides.”).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to dispose the gratings either on the same side or on opposite sides of the waveguide sheet as taught by Singer in the structure of the Calafiore – Chen – Lutolf – Singer combination because Singer teaches that either choice is an appropriate configuration for the couple-in and couple-out gratings (Singer paragraph [0074]).
Claims 13-14, 17-18 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Simmonds et al. US 2012/0120493 A1 (hereafter Simmonds).
Regarding claim 13, Calafiore teaches “An imaging device (waveguide 600), comprising: a diffraction grating structure (the grating structures of waveguide 600, see elements thereof below) comprising:
a waveguide sheet (substrate 602 of the waveguide 600) having a first end (portion where light from light source 604 enters the waveguide) and a second end (portion with grating line 618), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 6); …
a couple-out grating (An array of diffraction grating lines 618 paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. This also includes the ridges 312, 412 and 612. That the applicant was fully informed that 612 was being construed as part of the couple-out grating is self-evident from the arguments from the second to last paragraph of page 8 of 11 through the second paragraph of page 9 of 11 of the applicant’s remarks filed November 24, 2025. That 612 itself would be considered to be a grating is evident as follows. In paragraph [0031] Calafiore states: “The ridges 312 run parallel to one another in a plane parallel to the plane of the substrate 302 (perpendicular to the plane of FIGS. 3A and 3B) and have triangular cross-sections formed by first 321 and second 322 sides. Such a configuration is sometimes referred to as a blazed grating configuration.” As evidenced by Luo, a blazed structure of transparent material acts as a diffraction grating, even absent a coating layer thereon (see 1008 and 1012 in Fig. 10A and descriptions thereof). Furthermore, if the grating lines of Calafiore did not rest on a blazed structure, but rather were a continuous flat film, the device of Calafiore would not diffract light. Furthermore, an array of triangularly shaped ridges of an undisclosed transparent material with periods of 300 to 500 nm is a grating in the instant application, thus, this same structure in Calafiore with periods of 150 nm to 600 nm (paragraph [0046]) is also a diffraction grating. Lastly, Calafiore does not actually explicitly discuss the diffraction occurring due to any of the particular elements, thus the silence of Calafiore as to diffraction explicitly occurring due to the ridges cannot be taken as evidence that diffraction is not occurring. Rather, an ordinary skilled artisan would be sufficiently familiar with diffractive in-coupling and out-coupling elements in head-mounted displays to known that when an outcoupler is discloses as being a diffraction grating that it therefor operates under the regime of diffraction.) disposed at the second end of the waveguide sheet (see Fig. 6) and comprising a blazed grating (see Figs. 3C, 4A or 4B); and
a functional layer (grating lines 318, 418, 618) disposed on the couple-out grating (see Figs. 3C, 4A or 4B, 318,418 and 618 are on top of 312, 412 and 612), wherein: …
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).” emphasis added) to transmit the light coupled in the waveguide sheet … to the couple-out grating (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet (ridges 612, lines 618 and overcoat layer 624 are a diffraction grating device, see paragraph [0046]. Given that this is an out-coupling diffraction grating, an ordinary skilled artisan would reasonably deduce that it operates by diffraction.) to couple the light in the waveguide sheet out to the functional layer (see light-path in 612 in Fig. 6)… and
the functional layer is configured to refract the light coupled out by the couple-out grating to an ambient environment (paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. See paragraph [0032] the grating lines 318, 418 or 618 refract light because they are a slab of transparent material, such as silicon nitride (Si.sub.3N.sub.4), silicon oxide (SiO.sub.2), silicon oxynitride, siliconoxycarbonitride, a metal oxide, etc. where the refractive index of the array of grating lines 318 is different from the refractive index of the array of ridges 312.) and increase a light-outcoupling rate of the couple-out grating (Because the structure of the claimed system, as identified above is the same as that claimed, it must inherently perform the same function and increase a light-outcoupling rate of the couple-out grating. See MPEP §2114(I)) “If an examiner concludes that a functional limitation is an inherent characteristic of the prior art, then to establish a prima case of anticipation or obviousness, the examiner should explain that the prior art structure inherently possesses the functionally defined limitations of the claimed apparatus. In re Schreiber, 128 F.3d at 1478, 44 USPQ2d at 1432. See also Bettcher Industries, Inc. v. Bunzl USA, Inc., 661 F.3d 629, 639-40,100 USPQ2d 1433, 1440 (Fed. Cir. 2011).” In the instant case, the functional layer may be TiO2, one of the two preferred choices in the instant application, see claim 4, thus it will perform the same function),
wherein the functional layer is disposed on only the couple-out grating (Calafiore only discloses a couple-out grating and thus only discloses a functional layer on the couple-out grating) and covers all light couple-out surfaces of the couple-out grating (the functional layer 318, 418 or 618 covers each of the first sides 321, 421 and thus “all light couple-out surfaces” because light is only out-coupled from the waveguide toward the user via the angled first sides, not the second sides 322, 422. See e.g. out-coupling of the display light 655 in Fig. 6, paragraph [0046]);
the functional layer comprises a high refractive index film layer (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5); a refractive index of the functional layer is greater than or equal to 1.8 (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a refractive index of equal to or greater than 1.8 because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5)…
an image generation module (light source 604 which emits display light 605, see paragraph [0046]) … configured to emit light (see Fig. 6 and paragraph [0046]).”
However, Calafiore fails to explicitly teach “a couple-in grating disposed at the first end of the waveguide sheet and comprising a tilted grating; … the couple-in grating is configured to couple light in the waveguide sheet;… the waveguide sheet is configured to transmit the light coupled in the waveguide sheet by the couple-in grating…
an image generation module opposite to the couple-in grating and configured to emit light towards the couple-in grating; and
an optical module disposed between the image generation module and the couple-in grating, and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Chen teaches “An imaging device (Figs. 1, 3, 4, 5 or 7) comprising: a diffraction grating structure (Figs. 1, 3, 4, 5 or 7) comprising:
a waveguide sheet (lens body 10, waveguide 101, and/or waveguide 102, and/or waveguide 103)having a first end (the end with coupling-in region 11) and a second end (the end with coupling-out area 13), the first end and the second end being two opposite ends of the waveguide sheet (see Figs. 1, 3-5 or 7);
a couple-in grating (11 see paragraph [0050]: “incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure.”) disposed at the first end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a tilted grating (tilted grating 61);
a couple-out grating (13 see paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) disposed at the second end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a … grating (grating 61 or 62); and
… wherein:
the couple-in grating is configured to couple light in the waveguide sheet (paragraph [0050]: “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”);
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”) to transmit the light coupled in the waveguide sheet by the couple-in grating to the couple-out grating (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet (paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) to couple the light in the waveguide sheet out to … an ambient environment (paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13. After being diffracted by the nanostructure, the light is output to the human eye.”),
an image generation module (display screen 3) opposite to the couple-in grating (see e.g. Fig. 4) and configured to emit light towards the couple-in grating (paragraph [0051]: “the image light is emitted from the display screen 3”); and
an optical module (lens 4) disposed between the image generation module and the couple-in grating (see Fig. 4), and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Chen further teaches (paragraph [0050]): “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to introduce a couple-in grating opposite to the image generation module as taught by Chen into the display structure of Calafiore for the purpose of introducing the incident light at an angle that exhibits total internal reflection in the waveguide as taught by Chen thereby enabling the light to travel within the waveguide as designed.
However, Calafiore fails to teach “the couple-out grating is protruding out from the waveguide sheet or has a direct contact surface with the waveguide sheet.” Note however, that Calafiore teaches grating structures in Fig. 3C and Fig. 4B that protrude from the waveguide sheet with no overcoat layer thereon, however, it is ambiguous whether Figs. 3C and 4B represent only intermediate products or if they are also examples of a final configuration because paragraph [0035] states “Turning to FIG. 3D, the array of grating lines 318 may be over-coated with an overcoat layer 324 of material having a refractive index different from the material of the grating lines 318.” (emphasis added) and it is not clear whether the use of the verb “may” means that Calafiore also intends Fig. 3C to be a possible final product or if “may” is referring to the two options of the refractive index of the over-coat layer.
Lutolf teaches a waveguide-based display with incoupler gratings 100 and outcoupler gratings 102 that can be either arranged protruding out from the waveguide sheet as shown in Fig. 10a, 10b and 10d (for the outcoupling grating) or can be embedded into the optical substrate as shown in Fig. 10c.
Thus Calafiore discloses the claimed invention except that an embedded grating is used instead of a surface grating. Lutolf shows that a surface grating protruding out from the waveguide sheet is an equivalent structure in the art. Therefore, because these two out-coupling gratings were art-recognized equivalents before the effective filing date of the claimed invention, one of ordinary skill in the art would have found it obvious to substitute a surface grating for an embedded grating, and the results thereof would have been predictable. See MPEP §2144.06 and 2143 (I)(B).
However, Calafiore and Chen fail to explicitly teach “a thickness of the functional layer ranges from 20 nm to 150 nm;… an optical module disposed between the image generation module and the couple-in grating, and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Simmonds teaches “An imaging device (Fig. 1), comprising:
a diffraction grating structure (Fig. 1) comprising:
a waveguide sheet (waveguide 10) having a first end (the end with injection grating 16) and a second end (the end with plate waveguide 12), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 1);
a couple-in grating (injection grating 16) disposed at the first end of the waveguide sheet and comprising a tilted grating (see Fig. 1);
a functional layer disposed on the … grating (paragraph [0047]: “In a grating according to the invention (FIG. 4(b)) a conformal layer 34 of titanium dioxide approximately 70 nm thick is first applied to the grating 16.” and paragraph [0050]: “In one prototype, the titanium dioxide layer 60 was made 20 nm thick. In another, it was made 40 nm thick.”),
… wherein the couple-in grating is configured to couple light in the waveguide sheet (see Fig. 1), the waveguide sheet is configured to transmit the light coupled in the waveguide sheet by the couple-in grating (paragraph [0041]: “The rays (a typical one of which is shown at 18) thus are contained within the waveguide 10 between its parallel opposite surfaces, and propagate down the length of the waveguide 10.”) …
the functional layer comprises a high refractive index film layer (paragraphs [0047],[0050]: “titanium dioxide layer” Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Simmonds choice of titanium oxide also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claim 16); a refractive index of the functional layer is greater than or equal to 1.8 (paragraphs [0047],[0050]: “titanium dioxide layer” Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Simmonds choice of titanium oxide also has the property of a refractive index greater than or equal to 1.8, see e.g. claim 16); and a thickness of the functional layer ranges from 20 nm to 150 nm (paragraph [0047]: “a conformal layer 34 of titanium dioxide approximately 70 nm thick” paragraph [0050]: “In one prototype, the titanium dioxide layer 60 was made 20 nm thick. In another, it was made 40 nm thick.”);
an image generation module (that which generate image bearing light 14) opposite to the couple-in grating (see Fig. 1 the source of light 14 can be said to be opposite 16) and configured to emit light towards the couple-in grating (that is the function of the element that generates the image bearing light 14); and
an optical module (paragraph [0041]: “collimation optics (not shown)”) disposed between the image generation module and the couple-in grating (paragraph [0041]: “Collimated image bearing light 14 exits an optical arrangement which may be collimation optics (not shown), and is incident on an input reflection grating 16”), and configured to adjust the light emitted by the image generation module into parallel light (paragraph [0041]: “collimated image bearing light 14) at a predetermined angle to the couple-in grating (the angle between 14 and 16 is predetermined by the structural configuration of the device of Fig. 1).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate collimation optics as taught by Simmonds into the imaging device of the Calafiore – Chen combination for the purpose of introducing collimated light to the injection grating as taught by Simmonds.
Furthermore, the Calafiore – Chen combination discloses the claimed invention except for the thickness of the titanium oxide layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the thickness of the titanium oxide layer to be 20 nm to 150 nm such as 20 nm, 40 nm or 70 nm as taught by Simmonds, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the thickness of the high refractive index layer is an art recognized results effective variable in that it can be selected to reduce or suppress the rainbow effect as taught by Calafiore (paragraph [0027]. Thus one would have been motivated to optimize the thickness of the titanium oxide layer because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because Calafiore is silent regarding the particular choice of the thickness of the grating lines.
Regarding claim 14, the Calafiore – Chen – Lutolf – Simmonds combination teaches “The imaging device according to claim 13,” However Calafiore fails to explicitly teach “wherein:
a period of the couple-out grating ranges from 300 nm to 500 nm; and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees; and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees.”
Note that Calafiore does teach a period of the couple-out grating ranges from 150 nm to 600 nm (paragraph [0046]) and a blaze angle of the couple-out grating ranges from 30 to 60 degrees (paragraph [0046]). Furthermore, Calafiore teaches (paragraph [0024]): “At least one of pitch, duty cycle, height, slant angle, or refractive index of the array of grating lines is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light” where it should be noted that by the geometry of triangles, the anti-blaze angle contributes to the duty cycle, height and pitch of the grating lines for a given slant angle However, these disclosed ranges are too wide to be considered as anticipating the claimed ranges.
Simmonds teaches a coupling grating with a functional layer of titanium oxide (see e.g. paragraph [0050]) “wherein:
a period of the … grating ranges from 300 nm to 500 nm (paragraph [0050]: “The grating has a period of 435 nm”); and/or
a blaze angle of the couple-out grating ranges from 5 degrees to 40 degrees (this is optional); and/or
an anti-blaze angle of the couple-out grating ranges from 50 degrees to 85 degrees (this is optional).”
It has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I).
In the current instance Calafiore discloses a range of pitches between 150 nm and 600 nm which encompasses the narrower claimed range of 300 nm to 500 nm. Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose a value of the pitch within the narrower claimed range as taught by Simmonds, because it has been held that "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See MPEP §2144.05(I). Note that, in the current instance, the pitch is an art recognized results effective variable in that the pitch is selected to output portions of the display light at a plurality of offset locations along an optical path of the display light as taught by Calafiore (paragraph [0024]). Thus one would have been motivated to optimize the pitch because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because both Simmonds and Calafiore are directed to titanium oxide coated gratings within a waveguide-based head mounted display, where Simmonds teaches that a pitch of 435 nm is appropriate.
Regarding claim 17, the Calafiore – Chen – Lutolf – Simmonds combination teaches “The imaging device according to claim 13,” however, Calafiore fails to teach “wherein: the diffraction grating structure comprises three layers of waveguide sheets;
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively; and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively.”
Chen teaches (Fig. 7) “wherein: the diffraction grating structure comprises three layers of waveguide sheets (paragraph [0054]: “three layers of holographic diffraction waveguide lenses”);
the couple-in grating and the couple-out grating are distributed at two ends of each of the three layers of waveguide sheets, respectively (paragraph [0054]: “Among them, the functional areas of the three holographic diffraction waveguide lenses are composed of nano-diffraction gratings.” although not explicitly shown in Fig. 7, an ordinary skilled artisan would reasonably deduce that each of the waveguides contains a couple-in grating and a couple-out grating at the two ends thereof, as is true of Figs. 1-3, 5 and 6); and
the couple-in grating and the couple-out grating on each of the three layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light, to allow the couple-in gratings and the couple-out gratings on the three layers of waveguide sheets to diffract and reflect red light, green light, and blue light, respectively (paragraph [0054]: “The first diffractive waveguide lens 101, the second diffractive waveguide lens 102 and the third diffractive waveguide lens 103 are closely attached to each other in vertical space and are used to transmit red, green and blue image lights respectively… The period, height, duty cycle and other parameters of the nano-diffraction gratings corresponding to different lenses are different, and different lenses only couple and transmit one color image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen - Simmonds combination to have three waveguides one for each of red, green and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0054]).
Regarding claim 18, the Calafiore – Chen – Lutolf – Simmonds combination teaches “The imaging device according to claim 13,” however Calafiore is silent regarding “wherein: diffraction grating structure comprises two layers of waveguide sheets;
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively;
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light; and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light.”
Chen teaches (Figs. 4-6) “wherein: diffraction grating structure comprises two layers of waveguide sheets (a first diffractive waveguide lens 101 and a second diffractive waveguide lens 102);
the couple-in grating and the couple-out grating are distributed at two ends of each of the two layers of waveguide sheets, respectively (see Figs. 5 and 6);
the couple-in grating and the couple-out grating on one layer of the two layers of waveguide sheets are configured to diffract and reflect one of red light, green light, and blue light (paragraph [0052]: “the single-channel diffraction waveguide lens is used to couple the green image light”); and
the couple-in grating and the couple-out grating on the other layer of the two layers of waveguide sheets are configured to diffract and reflect remaining two of red light, green light, and blue light (paragraph [0052]: “The dual-channel diffraction waveguide lens is used to couple the image light of other colors. Preferably, the dual-channel diffraction waveguide lens is used to couple the blue image light and the red image light”).”
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to configure the head-mounted display of the Calafiore – Chen -Simmonds combination to have two waveguides one for green light and one for red and blue light, each with a couple-in grating and a couple-out grating as taught by Chen for the purpose of creating a full-color display as taught by Chen (paragraph [0052]).
Regarding claim 20, Calafiore teaches “A wearable apparatus (AR/VR display 800), comprising:
a housing (body or frame 802); and
an imaging device (display 804) disposed on the housing (see Fig. 8), wherein the imaging device comprises:
a diffraction grating structure (the grating structures of waveguide 600, see elements thereof below) comprising:
a waveguide sheet (substrate 602 of the waveguide 600) having a first end (portion where light from light source 604 enters the waveguide) and a second end (portion with grating line 618), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 6); …
a couple-out grating (An array of diffraction grating lines 618 paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. This also includes the ridges 312, 412 and 612. That the applicant was fully informed that 612 was being construed as part of the couple-out grating is self-evident from the arguments from the second to last paragraph of page 8 of 11 through the second paragraph of page 9 of 11 of the applicant’s remarks filed November 24, 2025. That 612 itself would be considered to be a grating is evident as follows. In paragraph [0031] Calafiore states: “The ridges 312 run parallel to one another in a plane parallel to the plane of the substrate 302 (perpendicular to the plane of FIGS. 3A and 3B) and have triangular cross-sections formed by first 321 and second 322 sides. Such a configuration is sometimes referred to as a blazed grating configuration.” As evidenced by Luo, a blazed structure of transparent material acts as a diffraction grating, even absent a coating layer thereon (see 1008 and 1012 in Fig. 10A and descriptions thereof). Furthermore, if the grating lines of Calafiore did not rest on a blazed structure, but rather were a continuous flat film, the device of Calafiore would not diffract light. Furthermore, an array of triangularly shaped ridges of an undisclosed transparent material with periods of 300 to 500 nm is a grating in the instant application, thus, this same structure in Calafiore with periods of 150 nm to 600 nm (paragraph [0046]) is also a diffraction grating. Lastly, Calafiore does not actually explicitly discuss the diffraction occurring due to any of the particular elements, thus the silence of Calafiore as to diffraction explicitly occurring due to the ridges cannot be taken as evidence that diffraction is not occurring. Rather, an ordinary skilled artisan would be sufficiently familiar with diffractive in-coupling and out-coupling elements in head-mounted displays to known that when an outcoupler is discloses as being a diffraction grating that it therefor operates under the regime of diffraction.) disposed at the second end of the waveguide sheet (see Fig. 6) and comprising a blazed grating (see Figs. 3C, 4A or 4B); and
a functional layer (grating lines 318, 418, 618) disposed on the couple-out grating (see Figs. 3C, 4A or 4B, 318, 418 and 618 are on top of 312, 412, and 612), wherein: …
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).” emphasis added) transmit the light coupled in the waveguide sheet … to the couple-out grating (paragraph [0046]: “The substrate 602 is configured to guide display light 605 emitted by a light source 604, e.g. a projection display, by total internal refection (TIR).”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet (ridges 612, lines 618 and overcoat layer 624 are a diffraction grating device, see paragraph [0046]. Given that this is an out-coupling diffraction grating, an ordinary skilled artisan would reasonably deduce that it operates by diffraction.) to couple the light in the waveguide sheet out to the functional layer (see light-path in 612 in Fig. 6)… and
the functional layer is configured to refract the light coupled out by the couple-out grating to an ambient environment (paragraph [0046]: “the array of grating lines 618 can be selected to output the portions 655 of the display light 605”. See paragraph [0032] the grating lines 318, 418 or 618 refract light because they are a slab of transparent material, such as silicon nitride (Si.sub.3N.sub.4), silicon oxide (SiO.sub.2), silicon oxynitride, siliconoxycarbonitride, a metal oxide, etc. where the refractive index of the array of grating lines 318 is different from the refractive index of the array of ridges 312.) and increase a light-outcoupling rate of the couple-out grating (Because the structure of the claimed system, as identified above is the same as that claimed, it must inherently perform the same function and increase a light-outcoupling rate of the couple-out grating. See MPEP §2114(I)) “If an examiner concludes that a functional limitation is an inherent characteristic of the prior art, then to establish a prima case of anticipation or obviousness, the examiner should explain that the prior art structure inherently possesses the functionally defined limitations of the claimed apparatus. In re Schreiber, 128 F.3d at 1478, 44 USPQ2d at 1432. See also Bettcher Industries, Inc. v. Bunzl USA, Inc., 661 F.3d 629, 639-40,100 USPQ2d 1433, 1440 (Fed. Cir. 2011).” In the instant case, the functional layer may be TiO2, one of the two preferred choices in the instant application, see claim 4, thus it will perform the same function),
wherein the functional layer is disposed on only the couple-out grating (Calafiore only discloses a couple-out grating and thus only discloses a functional layer on the couple-out grating) and covers all light couple-out surfaces of the couple-out grating (the functional layer 318, 418 or 618 covers each of the first sides 321, 421 and thus “all light couple-out surfaces” because light is only out-coupled from the waveguide toward the user via the angled first sides, not the second sides 322, 422. See e.g. out-coupling of the display light 655 in Fig. 6, paragraph [0046]);
the functional layer comprises a high refractive index film layer (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5); a refractive index of the functional layer is greater than or equal to 1.8 (paragraph [0028]: “a layer of a grating material, such as… TiO2”. Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Calafiore’s choice of TiO2 also has the property of a refractive index of equal to or greater than 1.8 because it is the same material as that disclosed in the instant application, see e.g. claims 4 and 5)…
an image generation module (light source 604 which emits display light 605, see paragraph [0046]) … configured to emit light (see Fig. 6 and paragraph [0046]).”
However, Calafiore fails to explicitly teach “a couple-in grating disposed at the first end of the waveguide sheet and comprising a tilted grating; … the couple-in grating is configured to couple light in the waveguide sheet;… the waveguide sheet is configured to transmit the light coupled in the waveguide sheet by the couple-in grating…
an image generation module opposite to the couple-in grating and configured to emit light towards the couple-in grating; and
an optical module disposed between the image generation module and the couple-in grating, and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Chen teaches “A wearable apparatus (Fig. 8), comprising:
a housing (the frame/body of Fig. 8); and an imaging device (51, 52) disposed on the housing (see Fig. 8), wherein the imaging device (Figs. 1, 3, 4, 5 or 7) comprises:
a diffraction grating structure (Figs. 1, 3, 4, 5 or 7) comprising:
a waveguide sheet (lens body 10, waveguide 101, and/or waveguide 102, and/or waveguide 103)having a first end (the end with coupling-in region 11) and a second end (the end with coupling-out area 13), the first end and the second end being two opposite ends of the waveguide sheet (see Figs. 1, 3-5 or 7);
a couple-in grating (11 see paragraph [0050]: “incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure.”) disposed at the first end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a tilted grating (tilted grating 61);
a couple-out grating (13 see paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) disposed at the second end of the waveguide sheet (see Figs. 1, 3-5 or 7) and comprising a … grating (grating 61 or 62); and
… wherein:
the couple-in grating is configured to couple light in the waveguide sheet (paragraph [0050]: “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”);
the waveguide sheet is configured to perform total reflection on the light coupled in the waveguide sheet (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”) to transmit the light coupled in the waveguide sheet by the couple-in grating to the couple-out grating (paragraph [0050]: “The light is transmitted along the total reflection direction and coupled to the turning region 12.”);
the couple-out grating is configured to perform diffraction on the light in the waveguide sheet ((paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13.”) to couple the light in the waveguide sheet out to … an ambient environment (paragraph [0050]: “The light is diffracted by the nanostructure and turned, and is transmitted to the coupling-out region 13. After being diffracted by the nanostructure, the light is output to the human eye.”),
an image generation module (display screen 3) opposite to the couple-in grating (see e.g. Fig. 4) and configured to emit light towards the couple-in grating (paragraph [0051]: “the image light is emitted from the display screen 3”); and
an optical module (lens 4) disposed between the image generation module and the couple-in grating (see Fig. 4), and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Chen further teaches (paragraph [0050]): “The incident image light is coupled to the diffraction waveguide lens 1, first enters the coupling-in region 11, and is diffracted by the nanostructure. The angle of the diffracted light satisfies the total reflection of the waveguide.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to introduce a couple-in grating opposite to the image generation module as taught by Chen into the wearable device of Calafiore for the purpose of introducing the incident light at an angle that exhibits total internal reflection in the waveguide as taught by Chen thereby enabling the light to travel within the waveguide as designed.
However, Calafiore fails to teach “the couple-out grating is protruding out from the waveguide sheet or has a direct contact surface with the waveguide sheet.” Note however, that Calafiore teaches grating structures in Fig. 3C and Fig. 4B that protrude from the waveguide sheet with no overcoat layer thereon, however, it is ambiguous whether Figs. 3C and 4B represent only intermediate products or if they are also examples of a final configuration because paragraph [0035] states “Turning to FIG. 3D, the array of grating lines 318 may be over-coated with an overcoat layer 324 of material having a refractive index different from the material of the grating lines 318.” (emphasis added) and it is not clear whether the use of the verb “may” means that Calafiore also intends Fig. 3C to be a possible final product or if “may” is referring to the two options of the refractive index of the over-coat layer.
Lutolf teaches a waveguide-based display with incoupler gratings 100 and outcoupler gratings 102 that can be either arranged protruding out from the waveguide sheet as shown in Fig. 10a, 10b and 10d (for the outcoupling grating) or can be embedded into the optical substrate as shown in Fig. 10c.
Thus Calafiore discloses the claimed invention except that an embedded grating is used instead of a surface grating. Lutolf shows that a surface grating protruding out from the waveguide sheet is an equivalent structure in the art. Therefore, because these two out-coupling gratings were art-recognized equivalents before the effective filing date of the claimed invention, one of ordinary skill in the art would have found it obvious to substitute a surface grating for an embedded grating, and the results thereof would have been predictable. See MPEP §2144.06 and 2143 (I)(B).
However, Calafiore and Chen fail to explicitly teach “a thickness of the functional layer ranges from 20 nm to 150 nm… an optical module disposed between the image generation module and the couple-in grating, and configured to adjust the light emitted by the image generation module into parallel light at a predetermined angle to the couple-in grating.”
Simmonds teaches “A wearable apparatus (paragraph [0001]: “head-mounted displays, helmet mounted displays”), comprising:
a housing (the frame or helmet); and
an imaging device disposed on the housing (the display is supported by the frame or helmet), wherein
the imaging device (Fig. 1), comprises:
a diffraction grating structure (Fig. 1) comprising:
a waveguide sheet (waveguide 10) having a first end (the end with injection grating 16) and a second end (the end with plate waveguide 12), the first end and the second end being two opposite ends of the waveguide sheet (see Fig. 1);
a couple-in grating (injection grating 16) disposed at the first end of the waveguide sheet and comprising a tilted grating (see Fig. 1);
a functional layer disposed on the … grating (paragraph [0047]: “In a grating according to the invention (FIG. 4(b)) a conformal layer 34 of titanium dioxide approximately 70 nm thick is first applied to the grating 16.” and paragraph [0050]: “In one prototype, the titanium dioxide layer 60 was made 20 nm thick. In another, it was made 40 nm thick.”),
… wherein the couple-in grating is configured to couple light in the waveguide sheet (see Fig. 1), the waveguide sheet is configured to transmit the light coupled in the waveguide sheet by the couple-in grating (paragraph [0041]: “The rays (a typical one of which is shown at 18) thus are contained within the waveguide 10 between its parallel opposite surfaces, and propagate down the length of the waveguide 10.”) …
the functional layer comprises a high refractive index film layer (paragraphs [0047],[0050]: “titanium dioxide layer” Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Simmonds choice of titanium oxide also has the property of a high refractive index because it is the same material as that disclosed in the instant application, see e.g. claim 16); a refractive index of the functional layer is greater than or equal to 1.8 (paragraphs [0047],[0050]: “titanium dioxide layer” Given that titanium oxide is one of the preferred materials of the high refractive index film layer, Simmonds choice of titanium oxide also has the property of a refractive index greater than or equal to 1.8, see e.g. claim 16); and a thickness of the functional layer ranges from 20 nm to 150 nm (paragraph [0047]: “a conformal layer 34 of titanium dioxide approximately 70 nm thick” paragraph [0050]: “In one prototype, the titanium dioxide layer 60 was made 20 nm thick. In another, it was made 40 nm thick.”);
an image generation module (that which generate image bearing light 14) opposite to the couple-in grating (see Fig. 1 the source of light 14 can be said to be opposite 16) and configured to emit light towards the couple-in grating (that is the function of the element that generates the image bearing light 14); and
an optical module (paragraph [0041]: “collimation optics (not shown)”) disposed between the image generation module and the couple-in grating (paragraph [0041]: “Collimated image bearing light 14 exits an optical arrangement which may be collimation optics (not shown), and is incident on an input reflection grating 16”), and configured to adjust the light emitted by the image generation module into parallel light (paragraph [0041]: “collimated image bearing light 14) at a predetermined angle to the couple-in grating (the angle between 14 and 16 is predetermined by the structural configuration of the device of Fig. 1).”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate collimation optics as taught by Simmonds into the imaging device of the Calafiore – Chen combination for the purpose of introducing collimated light to the injection grating as taught by Simmonds.
Furthermore, the Calafiore – Chen combination discloses the claimed invention except for the thickness of the titanium oxide layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the thickness of the titanium oxide layer to be 20 nm to 150 nm such as 20 nm, 40 nm or 70 nm as taught by Simmonds, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the thickness of the high refractive index layer is an art recognized results effective variable in that it can be selected to reduce or suppress the rainbow effect as taught by Calafiore (paragraph [0027]. Thus one would have been motivated to optimize the thickness of the titanium oxide layer because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because Calafiore is silent regarding the particular choice of the thickness of the grating lines.
Claim 16 is rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Simmonds et al. US 2012/0120493 A1 (hereafter Simmonds) as applied to claim 13 above, and further in view of Zheng et al. CN 110426850 A (hereafter Zheng, where reference will be made to the attached machine translation).
Regarding claim 16, the Calafiore – Chen – Lutolf - Simmonds combination teaches “The imaging device according to claim 13,” and Calafiore further teaches “wherein the functional layer comprises the titanium oxide film layer (paragraph [0028]: “a layer of grating material such as … TiO2”), … or the functional layer comprises a zirconium oxide film layer, and the thickness of the functional layer is 110 nm (this is optional).”
However, Calafiore fails to explicitly teach “the thickness of the functional layer is 90 nm.”
Note that Calafiore does teach “the refractive indices of the grating lines 202 and the substrate 204, the tilt angle α, the thickness t, and/or the duty cycle k of the grating lines 202 may be selected to reduce or suppress the rainbow effect” (paragraph [0027]).
Zheng teaches a coated diffraction grating for a waveguide-based display. Zheng further teaches “wherein when the functional layer comprises the titanium oxide film layer (paragraph [0011]: “the material of the high refractive index film layer”), a thickness of the functional layer is 90 nm (paragraph [0011]: “The thickness of the high refractive index film layer is 5nm to 150nm”).”
Zheng further teaches (paragraph [0007]): “the present invention aims to propose a single-layer full-color coupled waveguide display grating coupler, which should have the performance of achieving high efficiency coupling of a single-layer waveguide grating in a wider visible spectrum range. To this end, the technical solution adopted by the present invention is a single-layer full-color coupled waveguide display grating coupler, including: a waveguide, i.e. a transparent substrate, a grating layer of the same material or with a similar refractive index as the transparent substrate layer, a high refractive index material film layer on the grating layer, and a metal film layer on the high refractive index material. The morphology, period, groove depth, groove top angle, material of the grating layer, the thickness and refractive index of the high refractive index layer, and the thickness and refractive index of the metal film layer make the grating have a high first-order diffraction efficiency of more than 70% in the visible light spectrum range of 450nm-700nm.”
Thus the Calafiore – Chen – Lutolf – Simmonds combination discloses the claimed invention except for the thickness of the titanium oxide layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to optimize the thickness of the titanium oxide layer to be 90 nm, within the range of 5 to 150 nm taught by Zheng, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art, In re Aller, 105 USPQ 233 (C.C.P.A. 1955). In the current instance, the thickness of the high refractive index layer is an art recognized results effective variable in that it impacts the first-order diffraction efficiency for visible light as taught by Zheng paragraph [0007] and can be selected to reduce or suppress the rainbow effect as taught by Calafiore (paragraph [0027]. Thus one would have been motivated to optimize the thickness of the titanium oxide layer because it is an art-recognized result-effective variable and it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977). See MPEP §2144.05(II)(B) “after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a personal of ordinary skill in the art to experiment to reach another workable product or process.” Furthermore, one of ordinary skill in the art would have a reasonable expectation of success when making this modification because Calafiore is silent regarding the particular choice of the thickness of the grating lines.
Claim 19 rejected under 35 U.S.C. 103 as being unpatentable over Calafiore US 2020/0158943 A1 (cited in an IDS, hereafter Calafiore), in view of Chen et al. CN 210835313 U (hereafter Chen, where reference will be made to the attached machine translation), Lutolf et al. US 2016/0274281 A1 (hereafter Lutolf) and Simmonds et al. US 2012/0120493 (hereafter Simmonds) as applied to claim 13 above, and further in view of Singer et al. US 2020/0271847 A1 (cited in an IDS, hereafter Singer).
Regarding claim 19, the Calafiore – Chen – Lutolf - Simmonds combination teaches “The imaging device according to claim 13,” and Calafiore further teaches “wherein the diffraction grating comprises one layer of waveguide sheet (Fig. 6 substrate 602); and
the couple-in … and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively, (see Fig. 6 light is coupled-in at the upper end of 602 and the couple-out grating is at the bottom end of 602) and configured to diffract and reflect red light, green light, and blue light (e.g. paragraph [0046]: “operation with visible light” which is at least one of these colors).”
However, Calafiore fails to explicitly teach “the couple-in grating and the couple-out grating are … configured to diffract and reflect red light, green light, and blue light.”
Chen teaches “the diffraction grating comprises one layer of waveguide sheet (Figs. 1-3) the couple-in grating and the couple-out grating are … configured to diffract and reflect red light … and blue light (paragraph [0017]: “the dual-channel diffraction waveguide lens is used to couple blue image light and red image light.”).”
Singer teaches a waveguide-based head-mounted display with input coupling gratings 26 and output coupling gratings 28, “the diffraction grating structure comprises one layer of waveguide sheet (single light guide 20); and
the couple-in grating and the couple-out grating are distributed at two ends of the one layer of waveguide sheet, respectively (see Fig. 1), configured to diffract and reflect (paragraph [0072]: “the output coupling gratings 46′ can be partly transmissive and partly reflective, i.e., the output coupling gratings diffract the incident light partly in transmission and partly in reflection.”) red light, green light, and blue light (paragraph [0036]: “For the purposes of transmitting a chromatically larger spectral range, the transmitted field angle range can be reduced since chromatic effects compensate during input and output coupling or there is the option of manufacturing color multiplexing with, e.g., two or three tilted grating stacks in a light guide for the three colors of red, green and blue (RGB).” ).”
Singer further teaches (paragraph [0050]): “In the shown exemplary embodiment, the light guide arrangement 18 only has a single light guide 20, which is advantageous in view of a little complex and thin construction of the light guide arrangement 18.”
Thus it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to choose to construct the waveguide-based display from a single waveguide as taught by Chen Figs. 1-3 and Singer because Singer teaches that a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]).
Chen teaches that a single waveguide can diffract and guide both red and blue light, which have the largest and smallest wavelengths, and Singer teaches that because the chromatic effects are compensated during input and output coupling a chromatically larger spectral range can be transmitted, and that such a single waveguide is an alternative to having three stacked waveguides, one for each of red, green and blue. Taken together Chen and Singer teach that one can construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to construct the couple-in and couple-out gratings to diffract and reflect red light, green light and blue light, because Singer teaches that an arrangement with a single light guide is advantageous in view of a little complex and thin construction of the light guide arrangement (paragraph [0050]), and both Chen and Singer teach that a full color image having red, green and blue light is desirable.
Response to Arguments
Applicant's arguments filed February 24, 2026 have been fully considered but they are not persuasive.
On page 2 of 4 of the applicant’s remarks the applicant first lists the rejections of the previous office action.
In the paragraph spanning pages 2 and 3 of 4 of the applicant’s remarks the applicant quotes from a portion of claim 1 that they will be arguing is not taught or suggested by the prior art. No argument is made in this paragraph.
In lines 3-6 of page 3 of 4 of the applicant’s remarks the applicant notes that the rejection relies on the entirety of 618 and 612 as the grating. No specific argument is made in this paragraph.
In lines 7-9 of page 3 of 4 of the applicant’s remarks the applicant argues that 318 cannot be interpreted as the functional layer because 618 does not cover all light out-coupling surfaces of the couple-out grating. It is not entirely clear what the applicant is arguing here. At a best guess, it appears that the applicant is arguing that 618 is not the functional layer because it does not cover itself. This argument is not persuasive for at least the following reasons. Firstly, because both the instant application and Calafiore disclose a blazed grating of ridges (312, 412 and 612 in Calafiore, 30 in the instant application) upon which a layer having a different refractive index is formed (318, 418, 618 in Calafiore, 40 in the instant application). Given the identity of structures, it is unclear how it would be possible that the combination of 312, 412, 612 and 318, 418, 618 would not meet the corresponding limitations in the claim regardless of how they were expressed. Secondly, there is nothing unusual about saying that the last layer of an optical element covers the couple-out surfaces thereof. Consider how layers are discussed in optical elements in general. If a spectacle lens includes, sequentially, a base lens, a hard-coat layer, an anti-reflective layer and an anti-fouling layer, one would still say that the anti-fouling layer covered the exterior surface of the lens even though it is also part of the lens as a whole.
In lines 10-14 of page 3 of 4 of the applicant’s remarks the applicant argues that the other cited documents also fail to teach “cover all light couple-out surfaces of the couple-out grating.” This argument is moot, because this feature is taught by the primary reference of Calafiore.
From line 15 of page 3 through line 6 of page 4 of 4 of the applicant’s remarks the applicant appears to argue that if the rejection were changed to rely upon element 624 of Calafiore as the functional layer, that 624 would not meet all of the limitations thereof and thus the rejection would be improper. This argument is moot because this is not the rejection made.
In lines 7-12 of the applicant’s remarks the applicant concludes that claims 1-20 are allowable for the reasons argued above. These arguments have been addressed above.
The request for an interview with the examiner in lines 16-18 of page 4 of 4 of the applicant’s remarks is denied. The nature and number of the outstanding issues of patentability are such that it does not appear that an interview would result in expediting allowance of the application at this time. See MPEP §713.01 (IV) “An interview should be had only when the nature of the case is such that the interview could serve to develop and clarify specific issues and lead to a mutual understanding between the examiner and the applicant, and thereby advance the prosecution of the application. … Where a complete reply to a first action includes a request for an interview, the examiner, after consideration of the reply, should grant such an interview request if it appears that the interview would result in expediting the allowance of the application.”
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/CARA E RAKOWSKI/ Primary Examiner, Art Unit 2872