DETAILED ACTION
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 .
Claim Objections
Claims 1, 14, 17, and 20 are objected to because of the following informalities:
Claim 1 recites “the generating the resonator-internal image”
This should be amended to recite “ generating the resonator-internal image”
Claim 1 recites “compensating of the thermally induced depolarizing effects is effected through… generating the resonator-internal image rotation is effected through”
This should be amended to recite “compensating of the thermally induced depolarizing effects is affected through… generating the resonator-internal image rotation is affected through”
Claim 14 recites “and optionally α2”
α2 is recited in Claim 10. Claim 14 depends on Claim 8 and does not depend from Claim 10. Therefore, α2 lacks proper antecedent basis
Claim 17 recites “an image rotation of the transversal beam image through an angle in an angular range from 60° to 150° is effected for each round trip of the laser radiation”
This should be amended to recite “an image rotation of the transversal beam image through an angle in an angular range from 60° to 150° is affected for each round trip of the laser radiation”
Claim 20 recites “α2”
α2 is recited in Claim 10. Claim 20 depends from Claim 15 which depends from Claim 9. Claim 10 is not in the chain of dependency. Therefore, α2 lacks proper antecedent basis.
Appropriate correction is required.
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 4, 6-12, 16, and 18 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Ishizu (US 2003/0128732 A1).
Regarding Claim 1, Ishizu discloses a method of operating an optical resonator ([0039] the horizontally polarized component is output via the polarizer 4 and is extracted outside the resonator as an output), the method comprising:
at least one of compensating thermally induced depolarizing effects in the optical resonator ([0034] Due to this image rotation, each time the light beam passes through a point on the laser rod section, the beam is moved on a circle concentric with the optical axis; by using a suitable ridgeline angle, the beam does not pass through the same spot again. This symmetrizes the laser beam excitation distribution relative to the optical axis of the laser rod. As the excitation is horizontal, radial non-uniformity of the excitation distribution is equalized, so that, in terms of the laser rod section, an excitation distribution is obtained that is equivalently dose to even. [0037] Also, a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation, is returned as an elliptically polarized beam tilted relative to the principal axis. From this light, the polarizer returns the original polarization component to the resonator, maintaining the oscillation. Examiner Note: The compensation of thermally induced depolarizing effects is achieved through the described rotational beam path and polarization control. By forcing the laser beam to trace a circular, concentric path through the laser rod, the system ensures that the beam avoids repeating through the same non-uniformly excited or thermally distorted regions, effectively symmetrizing the excitation distribution and mitigating the impact of thermal gradients. Furthermore, the polarizer actively selects the original polarization component from the returned elliptically polarized beam, maintaining the desired polarization state within the resonator); and
generating a resonator-internal image rotation, the optical resonator including a plurality of elements reflecting laser radiation including a retroreflective prism configured to effect multiple instances of total internal reflection ([0034] Each time the laser beam is reflected by a Porro prism, the image thereof is inverted in a direction perpendicular to the ridgeline of the Porro prism. Each time the beam is reflected back and forth in the resonator constituted by the two Porro prisms 1 and 2, the image is rotated through an angle that is twice the ridgeline angle formed by the Porro prism ridgelines. Due to this image rotation, each time the light beam passes through a point on the laser rod section, the beam is moved on a circle concentric with the optical axis), the retroreflective prism including
a first roof edge face pair effecting total internal reflection, consisting of two roof edge faces arrange perpendicularly to one another as a retroreflective part ([0037] a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation, is returned as an elliptically polarized beam tilted relative to the principal axis. From this light, the polarizer returns the original polarization component to the resonator, maintaining the oscillation. In this case, the optimum ridgeline angle is one that enables suppression of higher-order modes and the obtaining of optimum output coupling at the polarizer… In the case of a Nd:YAG laser using Porro prisms of fused quartz or BK7 glass, the optimal predetermined angle would be within the range 90.+-.30 degrees or 0.+-.30 degrees), and
a second face effecting total internal reflection or a second roof edge face pair effecting total internal reflection, the second roof edge face pair consisting of two roof edge faces arranged perpendicularly to one another in such a manner that laser radiation entering the retroreflective prism parallel to an optical axis of the optical resonator undergoes total internal reflection at an angle α on the second face or the second roof edge face pair before undergoing total internal reflection on the first roof edge face pair ([0034] Each time the laser beam is reflected by a Porro prism, the image thereof is inverted in a direction perpendicular to the ridgeline of the Porro prism. Each time the beam is reflected back and forth in the resonator constituted by the two Porro prisms 1 and 2, the image is rotated through an angle that is twice the ridgeline angle formed by the Porro prism ridgelines. Due to this image rotation, each time the light beam passes through a point on the laser rod section, the beam is moved on a circle concentric with the optical axis [0038] In the case of a resonator laser having two Porro prisms with orthogonal ridgelines, each time the laser beam is reflected back and forth, the ridgeline image always coincides with a Porro prism ridgeline, making it easy for dark and bright cross-shaped stripes to enter the mode pattern), and after a further total internal reflection at the angle α on the second face or the second roof edge face pair exits the retroreflective prism parallel to the optical axis of the resonator again ([0039] With the ridgeline of the Porro prism 1 being perpendicular to the plane of incidence of the polarizer 4, a laser beam reflected back by the Porro prism 1 does not undergo any change in its polarization. Accordingly, all of the light from the Porro prism 1 falling incident on the polarizer 4 is transmitted towards the Porro prism 2. With respect to light that passes through the laser rod 3 and is reflected back by the Porro prism 2 to again fall incident on the polarizer 4, due to the inclination of the ridgeline of the Porro prism 2, the light undergoes a change of polarization, becoming elliptically polarized light. Thus, the horizontally polarized component is output via the polarizer 4 and is extracted outside the resonator as an output. It is desirable to adjust the ridgeline angle of Porro prism 2 to obtain the optimum amount of output coupling and image rotation), wherein
compensating of the thermally induced depolarizing effects is effected through the arrangement of the faces in the retroreflective prism that effect total internal reflection and alignment of the retroreflective prism relative to the optical axis of the resonator ([0034] Due to this image rotation, each time the light beam passes through a point on the laser rod section, the beam is moved on a circle concentric with the optical axis; by using a suitable ridgeline angle, the beam does not pass through the same spot again. This symmetrizes the laser beam excitation distribution relative to the optical axis of the laser rod. As the excitation is horizontal, radial non-uniformity of the excitation distribution is equalized, so that, in terms of the laser rod section, an excitation distribution is obtained that is equivalently dose to even. [0037] Also, a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation, is returned as an elliptically polarized beam tilted relative to the principal axis. From this light, the polarizer returns the original polarization component to the resonator, maintaining the oscillation. Examiner Note: The compensation of thermally induced depolarizing effects is achieved through the described rotational beam path and polarization control. By forcing the laser beam to trace a circular, concentric path through the laser rod, the system ensures that the beam avoids repeating through the same non-uniformly excited or thermally distorted regions, effectively symmetrizing the excitation distribution and mitigating the impact of thermal gradients. Furthermore, the polarizer actively selects the original polarization component from the returned elliptically polarized beam, maintaining the desired polarization state within the resonator), and
the generating the resonator-internal image rotation is effected through the arrangement of the faces in the retroreflective prism that effect total internal reflection and alignment of the retroreflective prism relative to the optical axis of the optical resonator in combination with a further retroreflective prism ([0034] Each time the laser beam is reflected by a Porro prism, the image thereof is inverted in a direction perpendicular to the ridgeline of the Porro prism. Each time the beam is reflected back and forth in the resonator constituted by the two Porro prisms 1 and 2, the image is rotated through an angle that is twice the ridgeline angle formed by the Porro prism ridgelines. Due to this image rotation, each time the light beam passes through a point on the laser rod section, the beam is moved on a circle concentric with the optical axis).
Regarding Claim 4, Ishizu discloses an optical resonator for laser radiation ([0050] In the laser oscillator of FIG. 6, the output coupling level can be adjusted independently of the image rotation by rotating the wave plate 10 about the optical path of the resonator) comprising:
a plurality of elements reflecting the laser radiation ([0037] a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation); and
at least one active or optical non-linear medium ([0050] The output coupling level can also be adjusted by adjusting the voltage applied to the Pockel's cell Q-switch 6 Examiner Note: A Q-Switch is an active non-linear medium),
wherein at least one of the plurality of elements is a retroreflective prism that effects multiple instances of total internal reflection ([0037] a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation), the retroreflective prism including
a first roof edge face pair effecting total internal reflection, consisting of two roof edge faces arranged perpendicularly to one another as a retroreflective part, by which the first roof edge is formed part ([0037] a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation, is returned as an elliptically polarized beam tilted relative to the principal axis. From this light, the polarizer returns the original polarization component to the resonator, maintaining the oscillation. In this case, the optimum ridgeline angle is one that enables suppression of higher-order modes and the obtaining of optimum output coupling at the polarizer… In the case of a Nd:YAG laser using Porro prisms of fused quartz or BK7 glass, the optimal predetermined angle would be within the range 90.+-.30 degrees or 0.+-.30 degrees.), and
a second face effecting total internal reflection or a second roof edge face pair effecting total internal reflection, the second roof edge face pair consisting of two roof edge faces arranged perpendicularly to one another by which a second roof edge is formed ([0038] In the case of a resonator laser having two Porro prisms with orthogonal ridgelines, each time the laser beam is reflected back and forth, the ridgeline image always coincides with a Porro prism ridgeline, making it easy for dark and bright cross-shaped stripes to enter the mode pattern),
the first roof edge face pair and the second face or the second roof edge face pair being arranged in such a manner that laser radiation entering the retroreflective prism parallel to an optical axis of the optical resonator undergoes total internal reflection at an angle α on the second face or the second roof edge face pair before undergoing total internal reflection on the first roof edge face pair, and after a further total internal reflection at the angle α on the second face or the second roof edge face pair exits the retroreflective prism parallel to the optical axis of the optical resonator again ([0049] the incident beam 12 and outgoing beam 13 are shown as having separate locations. The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization, the setting of the Q-switch can be independently controlled, so that the laser beam image that was rotated according to the angle formed by the ridgelines is, in this case, rotated by the fast axis angle of the wave plate. The reference for the angle of prism rotation corresponding to the Porro prism ridgeline is a line connecting a first reflection point 14 and a second reflection point 15 in the prism. The angle that this line forms with the ridgeline of the Porro prism 1 is an angle on a circle concentric with the axis of the optical path in the laser rod 3 that is an angle other than 0 degrees, 90 degrees, 60 degrees, 45 degrees and 36 degrees, 30 degrees. While FIG. 7(a) shows the prism 9 composed of the two right angle prisms 9a and 9b, it can be constituted as a single prism, as in the case of the prism 9 shown in FIG. 7(b). In FIG. 7(a), reference numeral 16 denotes a third reflection point and 17 a fourth reflection point).
Regarding Claim 6, Ishizu discloses a Porro prism ([0037] a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation) or a further retroreflective prism that effects multiple instances of total internal reflection.
Regarding Claim 7, Ishizu discloses that the first roof edge is aligned vertically to a plane of incidence of the laser radiation on the second face or the second roof edge face pair (Fig. 7(a) Examiner Note: Fig. 7(a), reproduced below, shows the first roof edge (between 15 and 16) aligned vertically with the plane of incidence on the second face, notice the light moves vertically away from the second face at point 14 and towards the roof edge pair, showing the roof edge pair is aligned vertically).
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Regarding Claim 8, Ishizu discloses that the first roof edge is aligned parallel to a plane of incidence of the laser radiation on the second face or the second roof edge face pair ([0046] The same Q-switch pulse laser operation can be achieved using an acousto-optic (AO) Q-switch instead of a Pockel's cell Q-switch, in which case the angle of the ridgeline of Porro prism 1 will be parallel or perpendicular to the plane of incidence of the polarizer).
Regarding Claim 9, Ishizu discloses that the first roof edge is aligned at an angle β to a plane of incidence of the laser radiation on the second face or the second roof edge face pair, wherein 0° < β < 90° ([0049] The reference for the angle of prism rotation corresponding to the Porro prism ridgeline is a line connecting a first reflection point 14 and a second reflection point 15 in the prism. The angle that this line forms with the ridgeline of the Porro prism 1 is an angle on a circle concentric with the axis of the optical path in the laser rod 3 that is an angle other than 0 degrees, 90 degrees, 60 degrees, 45 degrees and 36 degrees, 30 degrees).
Regarding Claim 10, Ishizu discloses that the retroreflective prism has a third face that effects total internal reflection, the third face being arranged such that the laser radiation entering the retroreflective prism undergoes total internal reflection between the second roof edge face pair and the first roof edge face pair at an angle α2 at the third face ([0049] The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization Examiner Note: The third face that effects total internal reflection is the main entry/exit face of the prism shown in Fig. 7(a), reproduced above, with a pentagon shape).
Regarding Claim 11, Ishizu discloses that the first roof edge is aligned at an angle β to a plane of incidence of the laser radiation on the third face, wherein 0° < β < 90° ([0050] it is desirable to rotate the prisms 9 and 11 relative to each other to form an angle with a line connecting the first reflection point 13 and second reflecting point 14 of FIG. 7(a), that preferably is any angle but not 0 degrees, 90 degrees, 60 degrees, 45 degrees or 36 degrees, 30 degrees).
Regarding Claim 12, Ishizu discloses that the first roof edge is aligned vertically to a plane of incidence of the laser radiation on the third face (Fig. 7(a) Examiner Note: Fig. 7(a), reproduced above, depicts the structural arrangement of the retroreflective prism, where the first roof edge (defined by the intersection of faces 15 and 16) is fixed in a vertical orientation relative to the incident plane of the third face. This vertical alignment is a necessary geometric feature of the disclosed prism configuration, which dictates the path of the incident laser radiation on the third face).
Regarding Claim 16, Ishizu discloses an active or optical non-linear medium ([0050] The output coupling level can also be adjusted by adjusting the voltage applied to the Pockel's cell Q-switch 6 Examiner Note: A Q-Switch is an active non-linear medium), and
a Porro prism or a further retroreflective prism ([0037] Also, a laser beam entering a Porro prism on the laser rod side that has been linearly polarized by two total reflections in the Porro prisms and image rotation, is returned as an elliptically polarized beam tilted relative to the principal axis), wherein
the retroreflective prism is rotated through an angle of rotation ϕ about the optical axis of the optical resonator, by which a mirroring of a transverse beam image of the laser radiation inclined by the angle ϕ relative to the vertical axis is created upon reflection at the retroreflective prism, and the Porro prism or the further retroreflect prism effects a further mirroring of the transverse beam image ([0050] However, as shown in FIG. 8, a prism 11 that maintains the plane of polarization can also be used in place of the Porro prism 1. In the oscillator of FIG. 8, the prism 11 is located on the optical path of the plane of incidence of the polarizer 4. To form a plurality of optical paths in the laser rod 3 on a circle concentric with the optical axis and effect excitation having a uniform distribution, it is desirable to rotate the prisms 9 and 11 relative to each other to form an angle with a line connecting the first reflection point 13 and second reflecting point 14 of FIG. 7(a), that preferably is any angle but not 0 degrees, 90 degrees, 60 degrees, 45 degrees or 36 degrees, 30 degrees).
Regarding Claim 18, Ishizu discloses a polarizer for partial coupling out of the laser radiation ([0044] When near the 1/4-wavelength voltage is applied to the Q-switch, the light towards the polarizer turns to be an almost linear but elliptically polarized light whose major axis is nearly parallel to the incident plane of the polarizer, increasing the Q of the, laser cavity to be sufficient to start the laser oscillation).
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over Ishizu (US 2003/0128732 A1) in view of Lundstrom (US 4,408,334).
Regarding Claim 2, Ishizu teaches that the optical resonator further includes a laser resonator ([0050] In the laser oscillator of FIG. 6, the output coupling level can be adjusted independently of the image rotation by rotating the wave plate 10 about the optical path of the resonator).
Ishizu is not relied upon as teaching that the method further comprises compensating a birefringence that occurs in an active medium of the laser resonator.
However, Lundstrom teaches that the method further comprises compensating a birefringence that occurs in an active medium of the laser resonator ([Col. 2, ll. 4-29] (2) FIG. 1 is an optical schematic of a laser resonator used in the present invention. Such resonators are useful for military laser rangefinders and target designators. An active gain media 10, which can be Nd:YAG, is a laser rod which is subject to stress birefringence effects at high input power loading when flashlamp 12 is pumped. The laser resonator is formed by two Porro prisms which serve as end reflectors. The first Porro prism 14 changes the state of polarization of a reflected light ray to a degree which depends on the orientation of the prism roof edge 16 and the index of refraction, n, of the prism material. For simplicity, Porro prism 18 is assumed to be made of the same material. Porro prisms are often used because they impart a high degree of alignment stability to the resonator. The resonator is Q switched, pulsed, using a polarizer 20 and a Pockel cell 22 in combination as an output shutter. The output beam 24 of the laser is taken off of polarizer 20. The output coupling fraction of the resonator can be selected by proper choice of the prism index, n, and roof edge orientation. Stress birefringence within laser rod 10 changes the state of polarization depending on the transverse position of the ray. The output coupling fraction of the resonator will therefore depend on the transverse coordinates of the ray [Col. 4, ll. 3-4] By proper choice of M.sub.w, it is possible to compensate for the birefringence in laser rod).
Ishizu and Lundstrom are considered to be analogous to the claimed invention because they are both in the same field of optical resonator technology. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified the optical resonator of Ishizu to include the teaching of compensating for birefringence that occurs in an active medium of the laser resonator of Lundstrom with a reasonable expectation of success. This modification would have been motivated by the desire to mitigate the impact of thermally induced stress birefringence on the laser beam’s polarization state and output coupling efficiency. By integrating Lundstrom’s teaching of utilizing proper prism material and roof edge orientation to compensate for birefringence into Ishizu’s laser resonator system, the system can achieve improved beam quality and more uniform excitation distribution within the active medium. A person of ordinary skill in the art would recognize that this combined arrangement would yield the predictable result of stable resonator operation with reduced depolarizing effects.
Claims 3, 13, 15, 17, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Ishizu (US 2003/0128732 A1).
Regarding Claim 3, Ishizu teaches compensating a deterioration of a beam quality in an optical non-linear process in the optical resonator ([0044] As described above, when no voltage is applied to the Pockel's cell the light traveling from the Porro prism 2 towards the polarizer is an almost linear but elliptically polarized light whose major axis is parallel to the incident plane of the polarizer 4, which damps the Q of the laser cavity too low to start the laser oscillation. When near the 1/4-wavelength voltage is applied to the Q-switch, the light towards the polarizer turns to be an almost linear but elliptically polarized light whose major axis is nearly parallel to the incident plane of the polarizer, increasing the Q of the, laser cavity to be sufficient to start the laser oscillation. An optimal output coupling of the polarizer is obtained by reducing the reflectivity through the adjustments of the angle of the prism rotation or the voltage applied to the Pockel's cell [0045] the initiation trigger of laser oscillation by applying a voltage to the Q-switch enough after a drive current is applied to the LD's to establish sufficient excitation in the laser medium. In the case of a continuously exciting Q-switched laser, the voltage can be applied to the Q-switch at set intervals that are just long enough for the oscillation to finish [0049] With a prism that maintains the plane of polarization, the setting of the Q-switch can be independently controlled, so that the laser beam image that was rotated according to the angle formed by the ridgelines is, in this case, rotated by the fast axis angle of the wave plate. Examiner Note: Q Switching is a non-linear process).
While Ishizu does not explicitly use the term “compensating a deterioration of beam quality,” it would have been obvious to a person of ordinary skill in the art that the disclosed adjustments to the prism rotation and Pockel’s cell voltage serve as a compensatory mechanism to maintain the desired laser oscillation against fluctuations in beam quality. Specifically, in a non-linear process such as Q-switching, a person of ordinary skill in the art would recognize that these adjustments are standardly employed to maintain high-quality, stable oscillation and to compensate for beam quality degradation (e.g., thermal-induced fluctuations). Therefore, it would have been obvious to a person of ordinary skill in the art to have utilized the disclosed adjustments of Ishizu to compensation for a deterioration of beam quality in an optical non-linear process, with a reasonable expectation of success, in order to achieve stable laser performance.
Regarding Claim 13, Ishizu discloses that the first roof edge is aligned parallel to a plane of incidence of the laser radiation on the third face (Fig. 7(a) Examiner Note: Fig. 7(a), reproduced above, shows that the orientation of the first roof edge, formed by the intersection of faces 15 and 16, is fixed in a spatial relationship with the incident light path on the third face such that the roof edge resides within, or parallel to, the defined plane of incidence).
Although Ishizu describes the alignment relative to the light path, it would have been obvious to a person of ordinary skill in the art to characterize this structural arrangement as parallel to the plane of incidence. As the plane of incidence is fundamentally defined by the incident beam and the surface normal, the physical geometry depicted in Fig. 7(a) establishes this relationship. Configuring the roof edge in this manner represents a routine design choice to ensure polarization stability, providing no unexpected results and constituting a predictable variation of the prior art.
Regarding Claim 15, Ishizu teaches an active medium ([0050] The output coupling level can also be adjusted by adjusting the voltage applied to the Pockel's cell Q-switch 6 Examiner Note: A Q-Switch is an active non-linear medium), wherein the angles α and β are adjusted within a range of 45° ± 20° (([0049] the incident beam 12 and outgoing beam 13 are shown as having separate locations. The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization, the setting of the Q-switch can be independently controlled, so that the laser beam image that was rotated according to the angle formed by the ridgelines is, in this case, rotated by the fast axis angle of the wave plate. The reference for the angle of prism rotation corresponding to the Porro prism ridgeline is a line connecting a first reflection point 14 and a second reflection point 15 in the prism. The angle that this line forms with the ridgeline of the Porro prism 1 is an angle on a circle concentric with the axis of the optical path in the laser rod 3 that is an angle other than 0 degrees, 90 degrees, 60 degrees, 45 degrees and 36 degrees, 30 degrees. While FIG. 7(a) shows the prism 9 composed of the two right angle prisms 9a and 9b, it can be constituted as a single prism, as in the case of the prism 9 shown in FIG. 7(b). In FIG. 7(a), reference numeral 16 denotes a third reflection point and 17 a fourth reflection point) [0050] it is desirable to rotate the prisms 9 and 11 relative to each other to form an angle with a line connecting the first reflection point 13 and second reflecting point 14 of FIG. 7(a), that preferably is any angle but not 0 degrees, 90 degrees, 60 degrees, 45 degrees or 36 degrees, 30 degrees).
The disclosed range of “any angle” excluding specific values provides a broad teaching that overlaps with the claimed range. It would have been obvious to a person of ordinary skill in the art to select the range 45° ± 20°, even if it includes 45 degrees, because the reference identifies these values as preferred merely for “desirable” performance, not as structural impossibilities.
Regarding Claim 17, Ishizu teaches that the retroreflective prism and the Porro prism or the further retroreflective prism are arranged such that an image rotation of the transversal beam image through an angle in an angular range from 60° to 150° is effected for each round trip of the laser radiation in the optical resonator ([0049] The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization [0050] However, as shown in FIG. 8, a prism 11 that maintains the plane of polarization can also be used in place of the Porro prism 1. In the oscillator of FIG. 8, the prism 11 is located on the optical path of the plane of incidence of the polarizer 4. To form a plurality of optical paths in the laser rod 3 on a circle concentric with the optical axis and effect excitation having a uniform distribution, it is desirable to rotate the prisms 9 and 11 relative to each other to form an angle with a line connecting the first reflection point 13 and second reflecting point 14 of FIG. 7(a), that preferably is any angle but not 0 degrees, 90 degrees, 60 degrees, 45 degrees or 36 degrees, 30 degrees Examiner Note: Ishizu teaches that the reflected image is rotated by an angle that is twice the angle of prism rotation. By adjusting the relative orientation of the prisms as taught in the reference, any desired image rotation angle, including the claimed range of 60° to 150°, is achievable).
Ishizu teaches a laser resonator configuration where the relative rotation of prisms 9 and 11 dictates the rotation of the transverse beam image. Although the reference lists specific preferred angles to avoid, it explicitly contemplates the variable rotation of these components to achieve different optical outcomes. It would have been obvious to a person of ordinary skill in the art to utilize the disclosed mechanism to set an image rotation within the range of 60° to 150°, as this is a predictable application of the rotational adjustment capabilities already taught by the reference to optimize the resonator’s performance.
Regarding Claim 20, Ishizu discloses that the angle α2 has a value of 45° ± 20° ([0049]- [0050] The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization… it is desirable to rotate the prisms 9 and 11 relative to each other to form an angle with a line connecting the first reflection point 13 and second reflecting point 14 of FIG. 7(a), that preferably is any angle but not 0 degrees, 90 degrees, 60 degrees, 45 degrees or 36 degrees, 30 degrees Examiner Note: α2 corresponds to twice the angle of prism rotation; because the prism rotation can be set to any angle (excluding the specific values provided for preference), the range of 45° ± 20° is achievable through the disclosed rotational adjustment mechanism).
It would have been obvious to a person of ordinary skill in the art to select the claimed range of 45° ± 20° as a matter of routine optimization. Since Ishizu teaches that prism rotation is continuously adjustable, selecting a specific angular range is a predictable application of the already disclosed adjustment mechanism. The reference’s exclusion of certain discrete values does not teach away from the claimed range. In fact, it confirms the system’s wide tunability. Therefore, the claimed range represents an obvious subset for a designer seeking to optimize the resonator’s output.
Claims 5, 14, and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Ishizu (US 2003/0128732 A1) in view of Ichihashi (US 2020/0379248 A1).
Regarding Claim 5 Ishizu is not relied upon as teaching a retardation optical unit.
However, Ichihashi teaches a retardation optical unit ([0062] the quarter-wave plate 43 delays a phase of the polarized component corresponding to the optical axis a3 in the passing light L11 by a quarter wavelength).
Ishizu and Ichihashi are considered to be analogous to the claimed invention because they are both in the same field of laser resonator technology. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified the resonator of Ishizu to include the retardation optical unit of Ichihashi with a reasonable expectation of success. This modification would have been motivated by the desire to achieve precise control over the polarization state of the laser radiation. By integrating Ichihashi’s teaching of a quarter-wave plate into Ishizu’s optical resonator, the system can selectively delay the phase of polarized components. A person of ordinary skill in the art would recognize that this modification would yield the predictable result of improved beam polarization control and enhanced laser oscillator efficiency.
Regarding Claim 14, Ishizu teaches an active medium ([0050] The output coupling level can also be adjusted by adjusting the voltage applied to the Pockel's cell Q-switch 6 Examiner Note: A Q-Switch is an active non-linear medium) and that the angles α and optionally α2 are 45° ± 5° to a plane of incidence of the laser radiation on the second face or the second roof edge face pair ([0049] the incident beam 12 and outgoing beam 13 are shown as having separate locations. The outgoing beam has the same polarization state as the incident beam, but as in the case of the Porro prism configuration, the reflected image is rotated about the incident beam axis by an angle that is twice the angle of prism rotation. With a prism that maintains the plane of polarization, the setting of the Q-switch can be independently controlled, so that the laser beam image that was rotated according to the angle formed by the ridgelines is, in this case, rotated by the fast axis angle of the wave plate. The reference for the angle of prism rotation corresponding to the Porro prism ridgeline is a line connecting a first reflection point 14 and a second reflection point 15 in the prism. The angle that this line forms with the ridgeline of the Porro prism 1 is an angle on a circle concentric with the axis of the optical path in the laser rod 3 that is an angle other than 0 degrees, 90 degrees, 60 degrees, 45 degrees and 36 degrees, 30 degrees. While FIG. 7(a) shows the prism 9 composed of the two right angle prisms 9a and 9b, it can be constituted as a single prism, as in the case of the prism 9 shown in FIG. 7(b). In FIG. 7(a), reference numeral 16 denotes a third reflection point and 17 a fourth reflection point).
Ishizu is not relied upon as teaching a quarter-wave retardation optical unit with one fast and one slow axis.
However, Ichihashi teaches a quarter-wave retardation optical unit with one fast and one slow axis ([0032] The beam B of the laser emitter 31 has a fast axis a1 and a slow axis a2 which are orthogonal to each other. [0062] The light L11 travels from the s/p separator 42 in the +d1 direction, and then the light L11 passes through the quarter-wave plate 43. Assuming that the optical axis a3 is the slow axis, the quarter-wave plate 43 delays a phase of the polarized component corresponding to the optical axis a3 in the passing light L11 by a quarter wavelength. Light L12 traveling in the +d1 direction through the quarter-wave plate 43 is reflected by the mirror 44. The reflected light L21 travels in the −d1 direction, passes through the quarter-wave plate 43 again, and is incident on the s/p separator 42.).
Ishizu and Ichihashi are considered to be analogous to the claimed invention because they are both in the same field of laser resonator technology. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified the laser resonator of Ishizu to include the retardation optical unit of Ichihashi with a reasonable expectation of success. This modification would have been motivated by the desire to improve control over the laser radiation’s polarization state within the resonator. By integrating Ichihashi’s teaching of a quarter-wave retardation optical unit with one fast and one slow axis into Ishizu’s laser resonator, the system can precisely manipulate the phase of the polarized light components. A person of ordinary skill in the art would recognize that this modification would yield the predictable result of enhanced laser beam quality and improved resonator output characteristics.
Regarding Claim 19, Ishizu is not relied upon as teaching that the optical resonator further includes a retardation optical unit.
However, Ichihashi teaches that the optical resonator further includes a retardation optical unit ([0062] the quarter-wave plate 43 delays a phase of the polarized component corresponding to the optical axis a3 in the passing light L11 by a quarter wavelength).
Ishizu and Ichihashi are considered to be analogous to the claimed invention because they are both in the same field of laser resonator technology. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified the laser resonator of Ishizu to include the retardation optical unit of Ichihashi with a reasonable expectation of success. This modification would have been motivated by the desire to improve control over the laser radiation’s polarization state within the resonator. By integrating Ichihashi’s teaching of a quarter-wave plate into Ishizu’s optical resonator, the system can selectively delay the phase of polarized components. A person of ordinary skill in the art would recognize that this modification would yield the predictable result of enhanced control over the resonator’s output characteristics.
Conclusion
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/E.H.H./Patent Examiner, Art Unit 3645
/HELAL A ALGAHAIM/SPE , Art Unit 3645
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