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 .
Status of the Claims
Claims 1 and 22-24 are amended. Claims 2-6, 8, and 10-21 are as previously presented. Claims 7 and 9 are cancelled. Therefore, claims 1-6, 8, and 10-24 are currently pending and have been considered below.
Response to Amendment
The amendment filed on December 30, 2026 has been entered.
Response to Arguments
Applicant’s arguments, see Pages 15-18, filed on 12/30/2025, with respect to the rejection(s) of claim(s) 1-6, 8, and 10-24 under U.S.C. 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of applicant’s amendment regarding the fixed length reference optical path and the interference fringes being in a position relative to the interference fringes at a predetermined nominal separation distance and newly found prior art regarding these features.
It is the Examiner’s position that arguments focused on Molnar combined with Schoenleber would be helpful.
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copy has been filed in parent Application No. IT102019000023181, filed on 12/06/2019.
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Allowable Subject Matter
Claim 17 and 19 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Claim Interpretation
The following is a quotation of 35 U.S.C. 112(f):
(f) Element in Claim for a Combination. – An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
The following is a quotation of pre-AIA 35 U.S.C. 112, sixth paragraph:
An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
The claims in this application are given their broadest reasonable interpretation using the plain meaning of the claim language in light of the specification as it would be understood by one of ordinary skill in the art. The broadest reasonable interpretation of a claim element (also commonly referred to as a claim limitation) is limited by the description in the specification when 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is invoked.
As explained in MPEP § 2181, subsection I, claim limitations that meet the following three-prong test will be interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph:
(A) the claim limitation uses the term “means” or “step” or a term used as a substitute for “means” that is a generic placeholder (also called a nonce term or a non-structural term having no specific structural meaning) for performing the claimed function;
(B) the term “means” or “step” or the generic placeholder is modified by functional language, typically, but not always linked by the transition word “for” (e.g., “means for”) or another linking word or phrase, such as “configured to” or “so that”; and
(C) the term “means” or “step” or the generic placeholder is not modified by sufficient structure, material, or acts for performing the claimed function.
Use of the word “means” (or “step”) in a claim with functional language creates a rebuttable presumption that the claim limitation is to be treated in accordance with 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. The presumption that the claim limitation is interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is rebutted when the claim limitation recites sufficient structure, material, or acts to entirely perform the recited function.
Absence of the word “means” (or “step”) in a claim creates a rebuttable presumption that the claim limitation is not to be treated in accordance with 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. The presumption that the claim limitation is not interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is rebutted when the claim limitation recites function without reciting sufficient structure, material or acts to entirely perform the recited function.
Claim limitations in this application that use the word “means” (or “step”) are being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, except as otherwise indicated in an Office action. Conversely, claim limitations in this application that do not use the word “means” (or “step”) are not being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, except as otherwise indicated in an Office action.
Such claim limitations interpreted as falling within U.S.C. 112(f) are:
In claim 23:
means for generating a measurement beam
means for propagating said measurement beam
means for generating a reference beam
means for propagating said reference beam
means for detecting a position of a pattern of interference fringes
In claim 24:
means for controlling a relative position between said working head and said material
Because this/these claim limitation(s) is/are being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, it/they is/are being interpreted to cover the corresponding structure described in the specification as performing the claimed function, and equivalents thereof.
Reference is made to the Specification filed on 06/02/2022 for what each means plus function statement covers.
For claim 23:
means for generating a measurement beam is interpreted to cover the Para. 0080, “beam splitter”
means for propagating said measurement beam is interpreted to cover the Para. 0092, “reflective optical scanning system’s inclination”
means for generating a reference beam is interpreted to cover the Para. 0072, “a low coherence optical radiation source”, which is from Para. 0088, “reference beam R of said low coherence optical radiation is generated by the same source 100”
means for propagating said reference beam is interpreted to cover the Para. 0081, “Both the measurement and reference optical beams are led through a cylindrical focusing lens 280”
means for detecting a position of a pattern of interference fringes is interpreted to cover the Para. 0074, “The detection of the fringe envelope may be carried out by means of optical intensity profile demodulation techniques”
In claim 24:
means for controlling a relative position between said working head and said material is interpreted to cover the Para. 0022, “Movement actuator means 40 are coupled to the processing head 14 and are controlled by the unit ECU for controlling the process by means of servomotors 42, in order to control the mechanical parameters of the process”
If applicant does not intend to have this/these limitation(s) interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, applicant may: (1) amend the claim limitation(s) to avoid it/them being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph (e.g., by reciting sufficient structure to perform the claimed function); or (2) present a sufficient showing that the claim limitation(s) recite(s) sufficient structure to perform the claimed function so as to avoid it/them being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph.
This application includes one or more claim limitations that use the word “means” or “step” but are nonetheless not being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph because the claim limitation(s) recite(s) sufficient structure, materials, or acts to entirely perform the recited function.
Such claim limitation(s) is/are: Claim 23, “processing means configured to determine a difference in optical length”, where “processing” provides structure
Because this/these claim limitation(s) is/are not being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, it/they is/are not being interpreted to cover only the corresponding structure, material, or acts described in the specification as performing the claimed function, and equivalents thereof.
If applicant intends to have this/these limitation(s) interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, applicant may: (1) amend the claim limitation(s) to remove the structure, materials, or acts that performs the claimed function; or (2) present a sufficient showing that the claim limitation(s) does/do not recite sufficient structure, materials, or acts to perform the claimed function.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-3, 8, 11, 14-15, and 20-24 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar).
Regarding claim 1, Schoenleber discloses a method for determining a separation distance between a working head in a machine for laser processing of a material (Abstract, “method for measuring the distance between a workpiece and a machining head of a laser machining apparatus”), operating by a high power processing laser beam emitted by said working head (Abstract, “a machining head is provided, which has a housing that has an interior and an opening for emergence of the laser radiation from the machining head.”) and led along a working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”), and a surface of the material at said working areas (Para. 0005, “By means of the robot, the machining head is then guided over the stationary workpiece”), the method comprising:
generating a measurement beam of low coherence optical radiation (Para. 0031, “It is easiest if the measuring beam is branched off from the object beam. The measuring beam then to a certain extent constitutes a second object beam”, where coherence tomographs use short coherence length light or low coherence optical radiation), leading said measurement beam towards a working area through said working head (Para. 0021, “a measuring beam, in addition to the object beam, passes through the interior, falsifications of the measured distance that have been caused by the described pressure fluctuations in the interior can be compensated. Ideally, the measuring beam passes through the interior close to the object beam, or even on the same light path”), and leading the measurement beam reflected or diffused from the surface of the material in said working area through said working head and towards an optical interferometric sensor arrangement along a first direction of incidence (Para. 0040, “The machining head additionally has an optical coherence tomograph, which is designed to measure the distance between the machining head and the workpiece during the laser machining operation, an object beam of the coherence tomograph likewise passing through the interior, emerging from the opening and being incident upon the workpiece during a measurement.”), in which the measurement beam travels a measurement optical path from a respective source to said optical interferometric sensor arrangement including a first section comprised between said respective source and the working head and a second section comprised between said working head and the interferometric sensor arrangement having a respective predetermined and invariant geometric length (Para. 0075, “In the object arm 70, measuring light 65 generated by the light source 64, after emerging from an optical fibre, is directed on to aaxicon 71”; Fig. 5, where the measuring light 65 includes a first section between the working head nozzle 56 and light source 64, where the distance does not change; Fig. 5, where the measuring light 65 includes a second section from the working head nozzle 56 area into a light sensor 79, Para. 0077, “a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24”, where the distance does not change);
generating a reference beam (Para. 0042, “The coherence tomograph has a detector, which is designed to detect a superimposition of a reflection of the measuring beam with another beam generated by the light source, for example a further object beam or the reference beam.”, where it is possible for a reference beam to be generated), wherein the reference beam travels a reference optical path whose optical length is equivalent to the optical length of the measurement optical path in a nominal operating condition in which a distance between the working head and the surface of the material corresponds to a predetermined nominal separation distance (Para. 0077, “The coherence tomograph 26 additionally includes a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24, by means of the reference light 73, which has traversed a similar optical path distance in the reference arm 72.”, where this optical path would be predetermined as the beam is used for reference);
superimposing the measurement beam and the reference beam on a common region of incidence of said optical interferometric sensor arrangement, along a predetermined illumination axis (Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph;”); and
determining a difference in optical length between the measurement optical path and the reference optical path, indicative of a difference between (a) a current separation distance between the working head and the surface of the material at the working area (Claim 1, “determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition”).
Schoenleber does not disclose:
generating a reference beam of said low coherence optical radiation, and leading said reference beam towards said optical interferometric sensor arrangement along a second direction of incidence, at a predetermined angle of incidence with respect to the first direction of incidence of said measurement beam;
detecting a position of a pattern of interference fringes between the measurement beam and the reference beam along said predetermined illumination axis on said common region of incidence, wherein an extension of said pattern of interference fringes along the predetermined illumination axis corresponds to a coherence length of said low coherence optical radiation; and
(b) the predetermined nominal separation distance, as a function of the position of said pattern of interference fringes along said predetermined illumination axis on said common region of incidence,
wherein the reference optical path has a fixed length, and the detected position of said pattern of interference fringes is a position relative to the position of said pattern of interference fringes at the predetermined nominal separation distance.
However, Otomo discloses, in the similar field of measuring distances using an interferometer, Page 1, Para. 2, “measuring apparatus for observing and inspecting the surface or internal irregularities of a sample (object to be measured) such as a wafer using an interferometer”, where there is a reference beam that is at a second direction of incidence compared to the measurement beam (Page 6, Para. 2 from end, “measuring apparatus includes a pulse laser 66, a collimating lens 68, a beam splitter 69, a long working objective lens 74, a glass plate 75, a test surface 77, a reference mirror 70”, where in Fig. 3, the measuring beam is 66 and the reference beam comes from 70, where these two beams are perpendicular to each other). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference beam in Schoenleber to include the perpendicular arrangement as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to determine in a singular interference image the height without needing to scan the laser light, as stated by Otomo, Page 7, Para. 2, “For example, the reference mirror 70 is fixed to a minute amount (in the best form, an angle of 15 minutes (that is, 15/60 degrees)) or is tilted (especially vibration) as necessary. By tilting, an interference fringe is formed on the area sensor 78. In this way, an interference image in the height direction can be obtained with one shot without scanning with laser light. In addition, the position of the interference end can be measured using a Michelson-type interferometer with low coherence.”.
Korner discloses, in the similar field of optical coherence tomography with interferometers (Abstract, “optical coherence tomography according to the Spatial Domain Approach (SD-OCT) and / or according to the light field approach. The arrangement comprises an interferometer”), where a position of the pattern of interference corresponds to a coherence length (Page 11, Para. 7-8 from end, “In the method for robust one-shot interferometry, spectral splitting in the detection beam path for increasing the coherence length and thus separating the interferograms of different wavelengths or wavelength ranges on the screened receiver are preferably carried out. The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”, where increasing coherence length can cause the interference pattern to separate out more, where this an intrinsic property of coherence length). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference detection in modified Schoenleber to include a correlation between coherence length and interference fringe patterns as taught by Korner.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to evaluate different wavelength of interference patterns, depending on a user’s needs, as stated by Korner, Page 11, Para. 7 from end, “The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”.
Further, Molnar discloses, in the similar field of measuring distances using an interferometer (Abstract, “a measuring device, in particular a length and angle measuring device, for measuring at least one change in position (Δx) and / or at least one change in angle (Δα), with a homodyne interferometer”), where a reference optical path has a fixed length (Page 3, Para. 4 from end, “reference reflector is understood to mean any device which is designed and arranged for reflecting the reference light beam. As a rule, this will be a reflector, such as a mirror, which is firmly fixed relative to the detector, the beam splitter and the beam source.”), where a detected position of pattern of interference fringes is a position relative to the interference fringes at a predetermined nominal separation distance (Abstract, “a homodyne interferometer (12) which has a beam splitter (30) for generating a reference Light beam(32) and a measuring light beam (34) from a primary light beam (26), a reference reflector (36) for reflecting the reference light beam (32), a movably guided measuring reflector (40) for reflecting the measurement -Light beam (34) and a detector (38), which are arranged so that the reference light beam (32) and the measuring light beam (34) interfere and when the measuring reflector (40) moves, a changing interference pattern ( 52.1) arises, the change of which can be detected by the detector(38).”, and where the change can be measured to determine the current separation distance, Page 2, Para. 2 from end, “a method for dynamically measuring at least one change in position and / or an angle of an object, comprising the steps of: (i) reading at least one line of an interference pattern of a homodyne interferometer so that detector readings are obtained; (ii) transforming the detector measurements into a frequency domain such that at least one phase and / or at least one frequency is obtained, and (iii) calculating the change in position from the at least one phase change and / or calculating the angles from the frequency change.”), where the predetermined nominal separation distance is a function of the position of the pattern of interference fringes (Fig. 5, where when length or the positioning changes, the difference in phase between the reference and measured patterns changes, where a predetermined nominal separation distance can be set as when both the reference and measured patterns are the same, where in modified Schoenleber, determining the distance between the machining head and workpiece would require setting a nominal value or a zeroed out value where the two patterns would be the same). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference pattern recognition system in modified Schoenleber to include the fixed reference optical length and preset nominal distance separation represented by an interference fringe pattern as taught by Molnar.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of using a singular light source to determine a separation distance, where the reference light source can be fixed in order to allow for easier comparison, and where the system becomes simpler to implement, as stated by Molnar, Page 3, Para. 1, “It is a further advantage that the measuring device according to the invention is constructed very simply. In a homodyne interferometer only one light source is necessary. It is also possible to form this light source as a stabilized light source, which can be easily compared with a frequency standard. The measuring device according to the invention thus allows a directly traceable measurement of the at least one position change.”.
Regarding claim 2, modified Schoenleber teaches the method according to claim 1, as set forth above.
Modified Schoenleber does not disclose:
wherein the position of the pattern interference fringes along the predetermined illumination axis is an intrinsic position of an intensity envelope of optical radiation of said pattern of interference fringes.
However, Otomo discloses where the pattern of interference fringes can be recorded in order to have the maximum value or peak shown, where this peak value would be an intrinsic position of the intensity of the interference fringe (Page 6, Para. 2, “As shown in FIG. 1C, when obtaining the maximum value (peak) of the waveform (focused wave), the waveform (focused wave) acquired by the CCDa 18 is multiplied by the stationary wave of the CCDb 20 to obtain the waveform (focused wave). It is preferable that the maximum value (peak) of the above is raised to facilitate detection.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference fringe waveform graph from modified Schoenleber to be a recording of the peak value as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to facilitate detection of the interference fringes, as stated by Otomo, Page 6, Para. 2, “It is preferable that the maximum value (peak) of the above is raised to facilitate detection.”.
Regarding claim 3, modified Schoenleber teaches the method according to claim 2, as set forth above, discloses wherein the intrinsic position of the intensity envelope of optical radiation of said pattern of interference fringes is the position of peak or maximum intensity envelope of said optical radiation (Teaching from Otomo, Page 6, Para. 2, “As shown in FIG. 1C, when obtaining the maximum value (peak) of the waveform (focused wave), the waveform (focused wave) acquired by the CCDa 18 is multiplied by the stationary wave of the CCDb 20 to obtain the waveform (focused wave). It is preferable that the maximum value (peak) of the above is raised to facilitate detection.”).
Regarding claim 8, modified Schoenleber teaches the method according to claim 1, as set forth above, discloses carried out in a machine for laser cutting, drilling or welding of a material or for additive manufacturing of three-dimensional structures by laser (Schoenleber, Para. 0079, “distance approximates as closely as possible to the specified distance d during the entire laser machining operation.”), wherein said machine comprises a working head having a nozzle for dispensing a flow of an assist gas, arranged proximate to said material, and the measurement beam is led through said nozzle and directed towards a measuring region of the material coaxial to said working area or adjacent to said working area, preferably in front of it along the working trajectory, or carried out-in a machine for laser welding of a material or additive manufacturing of three-dimensional structures by laser (Schoenleber, Para. 0080, “As already mentioned, during the laser machining operation the process gas passes through the interior 61, through which the laser radiation 21 and the measuring light 65 also pass.”, where the interior 61 includes a nozzle letting the laser radiation and gas out, where the measuring beam can be separate from the machining beam, Para. 0021, “a measuring beam, in addition to the object beam, passes through the interior, falsifications of the measured distance that have been caused by the described pressure fluctuations in the interior can be compensated. Ideally, the measuring beam passes through the interior close to the object beam, or even on the same light path”), wherein said machine comprises a working head having an output of the high power processing laser beam arranged in proximity of said material, and the measurement beam is led through said output of the high power processing beam and directed towards a measuring region of the coaxial to said working area or adjacent to said working area, preferably behind it along the working trajectory (Schoenleber, Para. 0080, “As already mentioned, during the laser machining operation the process gas passes through the interior 61, through which the laser radiation 21 and the measuring light 65 also pass.”, where regarding the specific configuration, Fig. 2 shows that the laser radiation 21 is in the middle, with process gas passing through the ending opening on one side of the laser radiation, Para. 0072, “process gas, supplied through the inlet opening 54, also emerges from the interior 61, through the bore 58 and the end opening 55”, and a measuring beam on the other side of the laser radiation, Para. 0083, “measuring beam 65b.”).
Regarding claim 11, modified Schoenleber teaches the apparatus according to claim 1, as set forth above, discloses wherein said predetermined illumination axis on the common region of incidence is determined by an intersection between a plane defined by said predetermined angle of incidence and a sensing surface of said optical interferometric sensor means arrangement (Schoenleber, Para. 0093, “As a result, the measuring beam 65b that has been reflected from the inner face 80' of the bore 58 is coupled back into the optical fibre of the object arm 70,jointly
with the reflected object beam.”, where there must be an intersection between the sensing surface of the interferometric sensor and the angle of incidence of the illumination plane in order for interference fringes to be detected).
Regarding claim 14, modified Schoenleber teaches the method according to claim 1, as set forth above, discloses wherein in a machine for laser cutting, drilling or welding of a material, or for additive manufacturing of three dimensional structures by laser comprising a working head having a nozzle for dispensing a flow of an assist gas in which the measurement beam is led through said nozzle (Schoenleber, Para. 0080, “As already mentioned, during the laser machining operation the process gas passes through the interior 61, through which the laser radiation 21 and the measuring light 65 also pass.”), the determination of the difference in optical length between the measurement optical path and the reference optical path is based on a normalized optical length of the measurement optical path which is calculated starting from a geometric length and from a normalized refractive index of a portion of said measurement optical path which passes through an assist gas chamber of the nozzle, which is calculated as a function of a pressure of the assist gas in said assist gas chamber, according to a predetermined nominal relationship of dependence of a refractive index of the assist gas upon the pressure of the assist gas (Schoenleber, Para. 0081, “The pressure fluctuations also involve fluctuations of the refractive index of the process gas, and this especially affects the accuracy of the distance measurement. Thus, if the process gas has, for example, a pressure of 5 bar at a first instant and of 1 bar at a second instant, then the distance values measured by the coherence tomograph 26 differ by more than 0.7 mm, if the distance between the protective glass 46 and the opening 55 is about 25 cm.”, where it is known that pressure of a gas can change the optical length measurements).
Regarding claim 15, modified Schoenleber teaches the method according to claim 1, as set forth above, discloses wherein the determination of the difference in optical length between the measurement optical path and the reference optical path is based on a normalized optical length of the measurement optical path which is calculated from a geometric length and from a normalized refractive index of a transmission medium of a portion of said measurement optical path, which is calculated as a function of temperature, pressure or other physical parameter of said portion of the measurement optical path according to a predetermined nominal relationship of dependence of a refractive index upon the temperature, pressure or other physical parameter of the transmission medium of the measurement beam (Schoenleber, Para. 0086, “In order to compensate falsifications of the measured workpiece distance dw that have been caused by pressure fluctuations in the interior 61, it is therefore merely necessary to correct the measured values dw by those fluctuations that are measured by the measuring beam 65b. The value dw' for the workpiece distance, compensated by the pressure fluctuations, is thus obtained as dw'Ct2)~dw(t2)-[ ( d,(12)-d,(t 1)]”, where the optical length takes into consideration the pressure within the chamber, as pressure fluctuations impact the accuracy of the distance measurements).
Regarding claim 20, modified Schoenleber teaches the method according to claim 1, as set forth above, discloses wherein the measurement beam incident (Schoenleber, Claim 1, “generating an object beam by means of a light source of an optical coherence tomograph, and directing the object beam on the workpiece”) on said optical interferometric sensor arrangement comprises a main measurement beam which results from travel of a main measurement optical path with reflection from the surface of the material in the working area and with transmission through at least one optical element interposed along an optical path of the high-power processing laser beam, and at least one additional multiplexed measurement beam which results from travel of an additional measurement optical path, with reflection from the surface of the material being processed and having a geometric length greater than the geometric length of said main measurement optical path, which includes at least a partial back-reflection at the surface of the at least one optical element interposed along the optical path of the high power processing laser beam,
the method comprising: detecting, on said common region of incidence, the position of an additional pattern of interference fringes having (i) a peak or maximum of intensity of optical radiation different from the peak or maximum of intensity of optical radiation of a main pattern of interference fringes between the main measurement beam and the reference beam, or (ii) an intrinsic position of an intensity of envelope of optical radiation offset from the intrinsic position of the intensity envelope of optical radiation of the main pattern of interference fringes; and
determining a difference in optical length between the additional measurement optical path and the reference optical path, indicative of a difference between (i) the current separation distance between the working head and the surface of the material at the working area and (ii) the predetermined nominal separation distance, as a function of the position of said additional pattern of interference fringes along said predetermined illumination axis of said common region of incidence.
Schoenleber discloses where there is a measurement beam that is used to determine separation distance (Claim 1, “generating an object beam by means of a light source of an optical coherence tomograph, and directing the object beam on the workpiece”). Schoenleber does not disclose where there are multiple measurement beams. However, it has been held that mere duplication of parts is an obvious modification to make. In re Harza, 274 F.2d 669, 124 USPQ 378 (CCPA 1960). Thus, duplicating the measurement beam would be a mere matter of user design choice.
Regarding claim 21, modified Schoenleber teaches the method according to claim 1, as set forth above, discloses wherein the reference beam incident (Schoenleber, Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph; f) determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition in step”) on said optical interferometric sensor arrangement comprises a main reference beam which results from travel of a main reference optical path and at least one additional multiplexed reference beam which results from travel of an additional reference optical path having a geometric length different from the geometric length of said main reference optical path,
the method comprising: detecting, on said common region of incidence, the position of an additional pattern of interference fringes having (i) a peak or maximum of intensity of optical radiation different from the peak or maximum of intensity of optical radiation of a main pattern of interference fringes between the main measurement beam and the reference beam, or (ii) an intrinsic position of an intensity of envelope of optical radiation offset from the intrinsic position of the intensity envelope of optical radiation of the main pattern of interference fringes; and
determining a difference in optical length between the additional measurement optical path and the reference optical path, indicative of a difference between (i) the current separation distance between the working head and the surface of the material at the working area and (ii) the predetermined nominal separation distance, as a function of the position of said additional pattern of interference fringes along said predetermined illumination axis of said common region of incidence.
Schoenleber discloses where there is a measurement beam that is used to determine separation distance (Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph; f) determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition in step”). Schoenleber does not disclose where there are multiple reference beams. However, it has been held that mere duplication of parts is an obvious modification to make. In re Harza, 274 F.2d 669, 124 USPQ 378 (CCPA 1960). Thus, duplicating the reference beam would be a mere matter of user design choice.
Regarding claim 22, Schoenleber discloses a method for controlling a relative position between a working head of a machine for laser processing of a material (Para. 0006, “It is ideal if the focal spot is tracked in a process of feedback control of the actually existing spatial arrangement of the workpieces. For this purpose, the actual spatial arrangement of the workpieces to be machined, relative to the machining head or to another reference point, is measured in real time during the laser machining operation.”), operating by a high power processing laser beam emitted by said working head and led along a working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”), and the material at said working areas (Para. 0005, “By means of the robot, the machining head is then guided over the stationary workpiece”), the method comprising
carrying out a method for determining a separation distance between a working head in a machine for laser processing of a material (Abstract, “method for measuring the distance between a workpiece and a machining head of a laser machining apparatus”), operating by a high power processing laser beam emitted by said working head and led along a working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”) and a surface of the material at said working areas (Para. 0005, “By means of the robot, the machining head is then guided over the stationary workpiece”), comprising
generating a measurement beam of low coherence optical radiation (Para. 0031, “It is easiest if the measuring beam is branched off from the object beam. The measuring beam then to a certain extent constitutes a second object beam”, where coherence tomographs use short coherence length light or low coherence optical radiation), leading said measurement beam towards a working area through said working head (Para. 0021, “a measuring beam, in addition to the object beam, passes through the interior, falsifications of the measured distance that have been caused by the described pressure fluctuations in the interior can be compensated. Ideally, the measuring beam passes through the interior close to the object beam, or even on the same light path”), and leading the measurement beam reflected or diffused from the surface of the material in said working area through said working head and towards an optical interferometric sensor arrangement along a first direction of incidence (Para. 0040, “The machining head additionally has an optical coherence tomograph, which is designed to measure the distance between the machining head and the workpiece during the laser machining operation, an object beam of the coherence tomograph likewise passing through the interior, emerging from the opening and being incident upon the workpiece during a measurement.”), in which the measurement beam travels a measurement optical path from a respective source to said optical interferometric sensor arrangement including a first section comprised between said respective source and the working head and a second section comprised between said working head and the interferometric sensor arrangement having a respective predetermined and invariant geometric length (Para. 0075, “In the object arm 70, measuring light 65 generated by the light source 64, after emerging from an optical fibre, is directed on to aaxicon 71”; Fig. 5, where the measuring light 65 includes a first section between the working head nozzle 56 and light source 64, where the distance does not change; Fig. 5, where the measuring light 65 includes a second section from the working head nozzle 56 area into a light sensor 79, Para. 0077, “a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24”, where the distance does not change),
generating a reference beam (Para. 0042, “The coherence tomograph has a detector, which is designed to detect a superimposition of a reflection of the measuring beam with another beam generated by the light source, for example a further object beam or the reference beam.”, where it is possible for a reference beam to be generated), wherein the reference beam travels a reference optical path whose optical length is equivalent to the optical length of the measurement optical path in a nominal operating condition in which a distance between the working head and the surface of the material corresponds to a predetermined nominal separation distance (Para. 0077, “The coherence tomograph 26 additionally includes a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24, by means of the reference light 73, which has traversed a similar optical path distance in the reference arm 72.”, where this optical path would be predetermined as the beam is used for reference);
superimposing the measurement beam and the reference beam on a common region of incidence of said optical interferometric sensor arrangement, along a predetermined illumination axis (Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph;”); and
determining a difference in optical length between the measurement optical path and the reference optical path, indicative of a difference between (a) a current separation distance between the working head and the surface of the material at the working area (Claim 1, “determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition”), and moving the working head towards or away from the material or in translation or inclination relative to the surface as a function of a predetermined working design and the determined separation distance between the working head and the surface of the material (Para. 0022, “The highly precise distance values may be used, for example, to keep the distance between the machining head and the workpiece to a specified value, by way of a feedback control. Additionally or alternatively, a feedback control of the position of the focal spot of the laser radiation may be effected by means of focussing optics arranged in the machining head, using the measured distances.”).
Schoenleber does not disclose:
generating a reference beam of said low coherence optical radiation, and leading said reference beam towards said optical interferometric sensor arrangement along a second direction of incidence, at a predetermined angle of incidence with respect to the first direction of incidence of said measurement beam,
detecting a position of a pattern of interference fringes between the measurement beam and the reference beam along said predetermined illumination axis on said common region of incidence, wherein an extension of said pattern of interference fringes along the predetermined illumination axis corresponds to a coherence length of said low coherence optical radiation; and
(b) the predetermined nominal separation distance, as a function of the position of said pattern of interference fringes along said predetermined illumination axis on said common region of incidence,
wherein the reference optical path has a fixed length, and the detected position of said pattern of interference fringes is a position relative to the position of said pattern of interference fringes at the predetermined nominal separation distance.
However, Otomo discloses, in the similar field of measuring distances using an interferometer, Page 1, Para. 2, “measuring apparatus for observing and inspecting the surface or internal irregularities of a sample (object to be measured) such as a wafer using an interferometer”, where there is a reference beam that is at a second direction of incidence compared to the measurement beam (Page 6, Para. 2 from end, “measuring apparatus includes a pulse laser 66, a collimating lens 68, a beam splitter 69, a long working objective lens 74, a glass plate 75, a test surface 77, a reference mirror 70”, where in Fig. 3, the measuring beam is 66 and the reference beam comes from 70, where these two beams are perpendicular to each other). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference beam in Schoenleber to include the perpendicular arrangement as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to determine in a singular interference image the height without needing to scan the laser light, as stated by Otomo, Page 7, Para. 2, “For example, the reference mirror 70 is fixed to a minute amount (in the best form, an angle of 15 minutes (that is, 15/60 degrees)) or is tilted (especially vibration) as necessary. By tilting, an interference fringe is formed on the area sensor 78. In this way, an interference image in the height direction can be obtained with one shot without scanning with laser light. In addition, the position of the interference end can be measured using a Michelson-type interferometer with low coherence.”.
Korner discloses, in the similar field of optical coherence tomography with interferometers (Abstract, “optical coherence tomography according to the Spatial Domain Approach (SD-OCT) and / or according to the light field approach. The arrangement comprises an interferometer”), where a position of the pattern of interference corresponds to a coherence length (Page 11, Para. 7-8 from end, “In the method for robust one-shot interferometry, spectral splitting in the detection beam path for increasing the coherence length and thus separating the interferograms of different wavelengths or wavelength ranges on the screened receiver are preferably carried out. The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”, where increasing coherence length can cause the interference pattern to separate out more, where this an intrinsic property of coherence length). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference detection in modified Schoenleber to include a correlation between coherence length and interference fringe patterns as taught by Korner.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to evaluate different wavelength of interference patterns, depending on a user’s needs, as stated by Korner, Page 11, Para. 7 from end, “The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”.
Further, Molnar discloses, in the similar field of measuring distances using an interferometer (Abstract, “a measuring device, in particular a length and angle measuring device, for measuring at least one change in position (Δx) and / or at least one change in angle (Δα), with a homodyne interferometer”), where a reference optical path has a fixed length (Page 3, Para. 4 from end, “reference reflector is understood to mean any device which is designed and arranged for reflecting the reference light beam. As a rule, this will be a reflector, such as a mirror, which is firmly fixed relative to the detector, the beam splitter and the beam source.”), where a detected position of pattern of interference fringes is a position relative to the interference fringes at a predetermined nominal separation distance (Abstract, “a homodyne interferometer (12) which has a beam splitter (30) for generating a reference Light beam(32) and a measuring light beam (34) from a primary light beam (26), a reference reflector (36) for reflecting the reference light beam (32), a movably guided measuring reflector (40) for reflecting the measurement -Light beam (34) and a detector (38), which are arranged so that the reference light beam (32) and the measuring light beam (34) interfere and when the measuring reflector (40) moves, a changing interference pattern ( 52.1) arises, the change of which can be detected by the detector(38).”, and where the change can be measured to determine the current separation distance, Page 2, Para. 2 from end, “a method for dynamically measuring at least one change in position and / or an angle of an object, comprising the steps of: (i) reading at least one line of an interference pattern of a homodyne interferometer so that detector readings are obtained; (ii) transforming the detector measurements into a frequency domain such that at least one phase and / or at least one frequency is obtained, and (iii) calculating the change in position from the at least one phase change and / or calculating the angles from the frequency change.”), where the predetermined nominal separation distance is a function of the position of the pattern of interference fringes (Fig. 5, where when length or the positioning changes, the difference in phase between the reference and measured patterns changes, where a predetermined nominal separation distance can be set as when both the reference and measured patterns are the same, where in modified Schoenleber, determining the distance between the machining head and workpiece would require setting a nominal value or a zeroed out value where the two patterns would be the same). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference pattern recognition system in modified Schoenleber to include the fixed reference optical length and preset nominal distance separation represented by an interference fringe pattern as taught by Molnar.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of using a singular light source to determine a separation distance, where the reference light source can be fixed in order to allow for easier comparison, and where the system becomes simpler to implement, as stated by Molnar, Page 3, Para. 1, “It is a further advantage that the measuring device according to the invention is constructed very simply. In a homodyne interferometer only one light source is necessary. It is also possible to form this light source as a stabilized light source, which can be easily compared with a frequency standard. The measuring device according to the invention thus allows a directly traceable measurement of the at least one position change.”.
Regarding claim 23, Schoenleber discloses a system for determining a separation distance between a working head in a machine for laser processing of a material (Abstract, “method for measuring the distance between a workpiece and a machining head of a laser machining apparatus”, where this method includes a system for using the method), operating by a high power processing laser beam emitted by said working head (Abstract, “a machining head is provided, which has a housing that has an interior and an opening for emergence of the laser radiation from the machining head.”) and led along a working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”), and a surface of the material at said working areas (Para. 0005, “By means of the robot, the machining head is then guided over the stationary workpiece”), the system comprising:
means for generating a measurement beam of low coherence optical radiation (Para. 0031, “It is easiest if the measuring beam is branched off from the object beam. The measuring beam then to a certain extent constitutes a second object beam”, where coherence tomographs use short coherence length light or low coherence optical radiation);
means for propagating said measurement beam, configured to lead said measurement beam towards a working area through said working head (Para. 0021, “a measuring beam, in addition to the object beam, passes through the interior, falsifications of the measured distance that have been caused by the described pressure fluctuations in the interior can be compensated. Ideally, the measuring beam passes through the interior close to the object beam, or even on the same light path”), and for leading the measurement beam reflected or diffused by the surface of the material in said working area through said working head towards an optical interferometric sensor arrangement along a first direction of incidence (Para. 0040, “The machining head additionally has an optical coherence tomograph, which is designed to measure the distance between the machining head and the workpiece during the laser machining operation, an object beam of the coherence tomograph likewise passing through the interior, emerging from the opening and being incident upon the workpiece during a measurement.”), in which the measurement beam travels a measurement optical path from a respective source to said optical interferometric sensor arrangement including a first section between said source and the working head and a second section between said working head and the interferometric sensor arrangement, having a respective predetermined and invariant geometric length (Para. 0075, “In the object arm 70, measuring light 65 generated by the light source 64, after emerging from an optical fibre, is directed on to aaxicon 71”; Fig. 5, where the measuring light 65 includes a first section between the working head nozzle 56 and light source 64, where the distance does not change; Fig. 5, where the measuring light 65 includes a second section from the working head nozzle 56 area into a light sensor 79, Para. 0077, “a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24”, where the distance does not change);
means for generating a reference beam of said low coherence optical radiation (Para. 0042, “The coherence tomograph has a detector, which is designed to detect a superimposition of a reflection of the measuring beam with another beam generated by the light source, for example a further object beam or the reference beam.”, where it is possible for a reference beam to be generated);
generating a reference beam, wherein the reference beam travels a reference optical path of optical length equivalent to the optical length of the measurement optical path in a nominal operating condition in which a distance between the working head and the surface of the material corresponds to a predetermined nominal separation distance (Para. 0077, “The coherence tomograph 26 additionally includes a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24, by means of the reference light 73, which has traversed a similar optical path distance in the reference arm 72.”, where this optical path would be predetermined as the beam is used for reference);
wherein the means for propagating the measurement beam and the means for propagating the reference beam are arranged to superimpose the measurement beam and the reference beam on a common region of incidence of said optical interferometric sensor arrangement, along a predetermined illumination axis (Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph;”); and
processing means configured to determine a difference in optical length between the measurement optical path and the reference optical path, indicative of a difference between (a) a current separation distance between the working head and the surface of the material at the working area (Claim 1, “determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition”).
Schoenleber does not disclose:
means for propagating said reference beam, configured to lead said reference beam towards said optical interferometric sensor arrangement along a second direction of incidence, at a predetermined angle of incidence with respect to the first direction incidence of said measurement beam,
means for detecting a position of a pattern of interference fringes between the measurement beam and the reference beam along said predetermined illumination axis on said common region of incidence, wherein an extension of said pattern of interference fringes along the predetermined illumination axis corresponds to a coherence length of said low coherence optical radiation; and
(b) the predetermined nominal separation distance, as a function of the position of said pattern of interference fringes along said predetermined illumination axis on said common region of incidence,
wherein the reference optical path has a fixed length, and the detected position of said pattern of interference fringes is a position relative to the position of said pattern of interference fringes at the predetermined nominal separation distance.
However, Otomo discloses, in the similar field of measuring distances using an interferometer, Page 1, Para. 2, “measuring apparatus for observing and inspecting the surface or internal irregularities of a sample (object to be measured) such as a wafer using an interferometer”, where there is a reference beam that is at a second direction of incidence compared to the measurement beam (Page 6, Para. 2 from end, “measuring apparatus includes a pulse laser 66, a collimating lens 68, a beam splitter 69, a long working objective lens 74, a glass plate 75, a test surface 77, a reference mirror 70”, where in Fig. 3, the measuring beam is 66 and the reference beam comes from 70, where these two beams are perpendicular to each other). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference beam in Schoenleber to include the perpendicular arrangement as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to determine in a singular interference image the height without needing to scan the laser light, as stated by Otomo, Page 7, Para. 2, “For example, the reference mirror 70 is fixed to a minute amount (in the best form, an angle of 15 minutes (that is, 15/60 degrees)) or is tilted (especially vibration) as necessary. By tilting, an interference fringe is formed on the area sensor 78. In this way, an interference image in the height direction can be obtained with one shot without scanning with laser light. In addition, the position of the interference end can be measured using a Michelson-type interferometer with low coherence.”.
Korner discloses, in the similar field of optical coherence tomography with interferometers (Abstract, “optical coherence tomography according to the Spatial Domain Approach (SD-OCT) and / or according to the light field approach. The arrangement comprises an interferometer”), where a position of the pattern of interference corresponds to a coherence length (Page 11, Para. 7-8 from end, “In the method for robust one-shot interferometry, spectral splitting in the detection beam path for increasing the coherence length and thus separating the interferograms of different wavelengths or wavelength ranges on the screened receiver are preferably carried out. The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”, where increasing coherence length can cause the interference pattern to separate out more, where this an intrinsic property of coherence length). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference detection in modified Schoenleber to include a correlation between coherence length and interference fringe patterns as taught by Korner.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to evaluate different wavelength of interference patterns, depending on a user’s needs, as stated by Korner, Page 11, Para. 7 from end, “The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”.
Further, Molnar discloses, in the similar field of measuring distances using an interferometer (Abstract, “a measuring device, in particular a length and angle measuring device, for measuring at least one change in position (Δx) and / or at least one change in angle (Δα), with a homodyne interferometer”), where a reference optical path has a fixed length (Page 3, Para. 4 from end, “reference reflector is understood to mean any device which is designed and arranged for reflecting the reference light beam. As a rule, this will be a reflector, such as a mirror, which is firmly fixed relative to the detector, the beam splitter and the beam source.”), where a detected position of pattern of interference fringes is a position relative to the interference fringes at a predetermined nominal separation distance (Abstract, “a homodyne interferometer (12) which has a beam splitter (30) for generating a reference Light beam(32) and a measuring light beam (34) from a primary light beam (26), a reference reflector (36) for reflecting the reference light beam (32), a movably guided measuring reflector (40) for reflecting the measurement -Light beam (34) and a detector (38), which are arranged so that the reference light beam (32) and the measuring light beam (34) interfere and when the measuring reflector (40) moves, a changing interference pattern ( 52.1) arises, the change of which can be detected by the detector(38).”, and where the change can be measured to determine the current separation distance, Page 2, Para. 2 from end, “a method for dynamically measuring at least one change in position and / or an angle of an object, comprising the steps of: (i) reading at least one line of an interference pattern of a homodyne interferometer so that detector readings are obtained; (ii) transforming the detector measurements into a frequency domain such that at least one phase and / or at least one frequency is obtained, and (iii) calculating the change in position from the at least one phase change and / or calculating the angles from the frequency change.”), where the predetermined nominal separation distance is a function of the position of the pattern of interference fringes (Fig. 5, where when length or the positioning changes, the difference in phase between the reference and measured patterns changes, where a predetermined nominal separation distance can be set as when both the reference and measured patterns are the same, where in modified Schoenleber, determining the distance between the machining head and workpiece would require setting a nominal value or a zeroed out value where the two patterns would be the same). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference pattern recognition system in modified Schoenleber to include the fixed reference optical length and preset nominal distance separation represented by an interference fringe pattern as taught by Molnar.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of using a singular light source to determine a separation distance, where the reference light source can be fixed in order to allow for easier comparison, and where the system becomes simpler to implement, as stated by Molnar, Page 3, Para. 1, “It is a further advantage that the measuring device according to the invention is constructed very simply. In a homodyne interferometer only one light source is necessary. It is also possible to form this light source as a stabilized light source, which can be easily compared with a frequency standard. The measuring device according to the invention thus allows a directly traceable measurement of the at least one position change.”.
Regarding claim 24, Schoenleber discloses a machine for laser processing of a material, operating by a high-power processing laser beam emitted by a working head (Abstract, “method for measuring the distance between a workpiece and a machining head of a laser machining apparatus”, where this method includes a system for using the method) and led along a
working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”), and including means for controlling a relative position between said working head and said material (Para. 0006, “It is ideal if the focal spot is tracked in a process of feedback control of the actually existing spatial arrangement of the workpieces. For this purpose, the actual spatial arrangement of the workpieces to be machined, relative to the machining head or to another reference point, is measured in real time during the laser machining operation.”), wherein the machine comprises a system for determining a separation distance between said working head and the surface of the material at said working areas, and is configured to carry out a method for determining a separation distance between a working head in a machine for laser processing of a material (Abstract, “method for measuring the distance between a workpiece and a machining head of a laser machining apparatus”), operating by a high power processing laser beam emitted by said working head (Abstract, “a machining head is provided, which has a housing that has an interior and an opening for emergence of the laser radiation from the machining head.”) and led along a working trajectory on the material comprising a succession of working areas (Para. 0004, “The machining head may be attached to a movable robot arm or to another positioning device that enables three-dimensional positioning.”) and a surface of the material at said working areas (Para. 0005, “By means of the robot, the machining head is then guided over the stationary workpiece”), comprising
generating a measurement beam of low coherence optical radiation (Para. 0031, “It is easiest if the measuring beam is branched off from the object beam. The measuring beam then to a certain extent constitutes a second object beam”, where coherence tomographs use short coherence length light or low coherence optical radiation), leading said measurement beam towards a working area through said working head (Para. 0021, “a measuring beam, in addition to the object beam, passes through the interior, falsifications of the measured distance that have been caused by the described pressure fluctuations in the interior can be compensated. Ideally, the measuring beam passes through the interior close to the object beam, or even on the same light path”), and leading the measurement beam reflected or diffused from the surface of the material in said working area through said working head and towards an optical interferometric sensor arrangement along a first direction of incidence (Para. 0040, “The machining head additionally has an optical coherence tomograph, which is designed to measure the distance between the machining head and the workpiece during the laser machining operation, an object beam of the coherence tomograph likewise passing through the interior, emerging from the opening and being incident upon the workpiece during a measurement.”), in which the measurement beam travels a measurement optical path from a respective source to said optical interferometric sensor arrangement including a first section comprised between said respective source and the working head and a second section comprised between said working head and the interferometric sensor arrangement having a respective predetermined and invariant geometric length (Para. 0075, “In the object arm 70, measuring light 65 generated by the light source 64, after emerging from an optical fibre, is directed on to aaxicon 71”; Fig. 5, where the measuring light 65 includes a first section between the working head nozzle 56 and light source 64, where the distance does not change; Fig. 5, where the measuring light 65 includes a second section from the working head nozzle 56 area into a light sensor 79, Para. 0077, “a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24”, where the distance does not change),
generating a reference beam (Para. 0042, “The coherence tomograph has a detector, which is designed to detect a superimposition of a reflection of the measuring beam with another beam generated by the light source, for example a further object beam or the reference beam.”, where it is possible for a reference beam to be generated), wherein the reference beam travels a reference optical path whose optical length is equivalent to the optical length of the measurement optical path in a nominal operating condition in which a distance between the working head and the surface of the material corresponds to a predetermined nominal separation distance (Para. 0077, “The coherence tomograph 26 additionally includes a spectrally resolving light sensor 79, which senses the interference of measuring light 65 that has been reflected from the workpiece 24, by means of the reference light 73, which has traversed a similar optical path distance in the reference arm 72.”, where this optical path would be predetermined as the beam is used for reference);
superimposing the measurement beam and the reference beam on a common region of incidence of said optical interferometric sensor arrangement, along a predetermined illumination axis (Claim 1, “superimposing the reflection of the object beam with a reference beam generated by the light source of the coherence tomograph;”);
determining a difference in optical length between the measurement optical path and the reference optical path, indicative of a difference between (a) a current separation distance between the working head and the surf ace of the material at the working area (Claim 1, “determining the distance between the machining head and the workpiece from an interference signal obtained by the superimposition”), and
said means for controlling the relative position between said working head and said material acting according to a predetermined working design and the determined separation distance between the working head and the surface of the material (Para. 0022, “The highly precise distance values may be used, for example, to keep the distance between the machining head and the workpiece to a specified value, by way of a feedback control. Additionally or alternatively, a feedback control of the position of the focal spot of the laser radiation may be effected by means of focussing optics arranged in the machining head, using the measured distances.”).
Schoenleber does not disclose:
generating a reference beam of said low coherence optical radiation, and leading said reference beam towards said optical interferometric sensor arrangement along a second direction of incidence, at a predetermined angle of incidence with respect to the first direction of incidence of said measurement beam,
detecting a position of a pattern of interference fringes between the measurement beam and the reference beam along said predetermined illumination axis on said common region of incidence, wherein an extension of said pattern of interference fringes along the predetermined illumination axis corresponds to a coherence length of said low coherence optical radiation; and
(b) the predetermined nominal separation distance, as a function of the position of said pattern of interference fringes along said predetermined illumination axis on said common region of incidence,
wherein the reference optical path has a fixed length, and the detected position of said pattern of interference fringes is a position relative to the position of said pattern of interference fringes at the predetermined nominal separation distance.
However, Otomo discloses, in the similar field of measuring distances using an interferometer, Page 1, Para. 2, “measuring apparatus for observing and inspecting the surface or internal irregularities of a sample (object to be measured) such as a wafer using an interferometer”, where there is a reference beam that is at a second direction of incidence compared to the measurement beam (Page 6, Para. 2 from end, “measuring apparatus includes a pulse laser 66, a collimating lens 68, a beam splitter 69, a long working objective lens 74, a glass plate 75, a test surface 77, a reference mirror 70”, where in Fig. 3, the measuring beam is 66 and the reference beam comes from 70, where these two beams are perpendicular to each other). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference beam in Schoenleber to include the perpendicular arrangement as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to determine in a singular interference image the height without needing to scan the laser light, as stated by Otomo, Page 7, Para. 2, “For example, the reference mirror 70 is fixed to a minute amount (in the best form, an angle of 15 minutes (that is, 15/60 degrees)) or is tilted (especially vibration) as necessary. By tilting, an interference fringe is formed on the area sensor 78. In this way, an interference image in the height direction can be obtained with one shot without scanning with laser light. In addition, the position of the interference end can be measured using a Michelson-type interferometer with low coherence.”.
Korner discloses, in the similar field of optical coherence tomography with interferometers (Abstract, “optical coherence tomography according to the Spatial Domain Approach (SD-OCT) and / or according to the light field approach. The arrangement comprises an interferometer”), where a position of the pattern of interference corresponds to a coherence length (Page 11, Para. 7-8 from end, “In the method for robust one-shot interferometry, spectral splitting in the detection beam path for increasing the coherence length and thus separating the interferograms of different wavelengths or wavelength ranges on the screened receiver are preferably carried out. The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”, where increasing coherence length can cause the interference pattern to separate out more, where this an intrinsic property of coherence length). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference detection in modified Schoenleber to include a correlation between coherence length and interference fringe patterns as taught by Korner.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to evaluate different wavelength of interference patterns, depending on a user’s needs, as stated by Korner, Page 11, Para. 7 from end, “The spectral splitting in the detection beam path causes an increase in the coherence length, which in turn causes an increase in the area with high-contrast evaluable interferences on the detector and thus also gives the possibility of performing a multi-wavelength evaluation with phase evaluation.”.
Further, Molnar discloses, in the similar field of measuring distances using an interferometer (Abstract, “a measuring device, in particular a length and angle measuring device, for measuring at least one change in position (Δx) and / or at least one change in angle (Δα), with a homodyne interferometer”), where a reference optical path has a fixed length (Page 3, Para. 4 from end, “reference reflector is understood to mean any device which is designed and arranged for reflecting the reference light beam. As a rule, this will be a reflector, such as a mirror, which is firmly fixed relative to the detector, the beam splitter and the beam source.”), where a detected position of pattern of interference fringes is a position relative to the interference fringes at a predetermined nominal separation distance (Abstract, “a homodyne interferometer (12) which has a beam splitter (30) for generating a reference Light beam(32) and a measuring light beam (34) from a primary light beam (26), a reference reflector (36) for reflecting the reference light beam (32), a movably guided measuring reflector (40) for reflecting the measurement -Light beam (34) and a detector (38), which are arranged so that the reference light beam (32) and the measuring light beam (34) interfere and when the measuring reflector (40) moves, a changing interference pattern ( 52.1) arises, the change of which can be detected by the detector(38).”, and where the change can be measured to determine the current separation distance, Page 2, Para. 2 from end, “a method for dynamically measuring at least one change in position and / or an angle of an object, comprising the steps of: (i) reading at least one line of an interference pattern of a homodyne interferometer so that detector readings are obtained; (ii) transforming the detector measurements into a frequency domain such that at least one phase and / or at least one frequency is obtained, and (iii) calculating the change in position from the at least one phase change and / or calculating the angles from the frequency change.”), where the predetermined nominal separation distance is a function of the position of the pattern of interference fringes (Fig. 5, where when length or the positioning changes, the difference in phase between the reference and measured patterns changes, where a predetermined nominal separation distance can be set as when both the reference and measured patterns are the same, where in modified Schoenleber, determining the distance between the machining head and workpiece would require setting a nominal value or a zeroed out value where the two patterns would be the same). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interference pattern recognition system in modified Schoenleber to include the fixed reference optical length and preset nominal distance separation represented by an interference fringe pattern as taught by Molnar.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of using a singular light source to determine a separation distance, where the reference light source can be fixed in order to allow for easier comparison, and where the system becomes simpler to implement, as stated by Molnar, Page 3, Para. 1, “It is a further advantage that the measuring device according to the invention is constructed very simply. In a homodyne interferometer only one light source is necessary. It is also possible to form this light source as a stabilized light source, which can be easily compared with a frequency standard. The measuring device according to the invention thus allows a directly traceable measurement of the at least one position change.”.
Claims 4-6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar) in further view of Wang et al. (US 8830475 B1, hereinafter Wang).
Regarding claim 4, modified Schoenleber teaches the method according to claim 1, as set forth above.
Modified Schoenleber does not disclose:
wherein said optical interferometric sensor arrangement comprises an arrangement of photodetectors along said predetermined illumination axis, and the predetermined angle of incidence is controlled so that a spatial frequency of said pattern of interference fringes is greater than a spatial frequency of the photodetectors of said arrangement of photodetectors.
However, Wang discloses, in the similar field of interferometers (Abstract, “Disclosed is an interferometer), where the photodetectors can detect interference fringes, where the spatial frequency of the photodetectors can be greater than that of the interference fringes (Page 5, Section 2, lines 53-56, “In addition, the photodetector can be an optical sensor array, preferably, the photodetector is a two-dimensional optical sensor array, whose density is at least greater than or equal to the spatial frequency of the plural interference fringe.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interferometer in modified Schoenleber to include the features as taught by Wang.
Regarding the spatial frequency being greater or lesser, it is the Examiner's position that one of ordinary skill in the art would have found it obvious to try as Wang discloses the advantage of having photodetector spatial frequency being greater than the interference fringes in providing for a comprehensive image, Page 5, Section 2, lines 60-63, “This design can enable the two-dimensional optical sensor array to comprehensively receive light information from an interference pattern.”. However, there are limited configurations in which photodetectors can be arranged that still provide the same end result of detecting interference fringes. It is the Examiner’s position that applying the advantage of Wang can be used in the opposite manner, where making the photodetector spatial frequency less than the interference fringes would allow for greater resolution of the image. Thus, altering the spatial frequency would be a mere matter of user design choice.
Regarding claim 5, modified Schoenleber teaches the method according to claim 4, as set forth above, discloses wherein the spatial frequency of said pattern of interference fringes is different from multiples of the spatial frequency of the photodetectors of said arrangement of photodetectors and preferably close to a half-integer multiple of said spatial frequency of photodetectors (Teaching from Wang, Page 5, Section 2, lines 53-56, “In addition, the photodetector can be an optical sensor array, preferably, the photodetector is a two-dimensional optical sensor array, whose density is at least greater than or equal to the spatial frequency of the plural interference fringe.”, where the altering the spatial frequency to be greater or lesser would include a variety of values that can include half-integer multiples).
Regarding claim 6, modified Schoenleber teaches the method according to claim 1, as set forth above.
Modified Schoenleber does not disclose:
wherein said optical interferometric sensor arrangement comprises an arrangement of photodetectors along said predetermined illumination axis and said arrangement of photodetectors is a linear arrangement of photodetectors or a two-dimensional arrangement of photodetectors.
However, Wang discloses, where the photodetectors can detect interference fringes, where the spatial frequency of the photodetectors can be a two dimensional array (Page 5, Section 2, lines 53-56, “In addition, the photodetector can be an optical sensor array, preferably, the photodetector is a two-dimensional optical sensor array, whose density is at least greater than or equal to the spatial frequency of the plural interference fringe.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interferometer in modified Schoenleber to include the features as taught by Wang.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to use a system that can comprehensively receive light information from interference patterns, as stated by Wang, Page 5, Section 2, lines 53-63, “In addition, the photodetector can be an optical sensor array, preferably, the photodetector is a two-dimensional optical sensor array…This design can enable the two-dimensional optical sensor array to comprehensively receive light information from an interference pattern.”.
Claims 10 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar) in further view of Webster (US 20190299327 A1).
Regarding claim 10, modified Schoenleber teaches the method according to claim 8, as set forth above.
Modified Schoenleber does not disclose:
wherein the measurement beam is directed towards said measuring region of the material by an optical scanning system whose inclination is controlled according to absolute value and direction of rate of advancement of the working head along the working trajectory.
However, Webster discloses, in the similar field of interferometers (Para. 0038, “While a Michelson-style interferometer was just described, other interferometer configurations”), where inclination of a scanning device can be adjusted according to the velocity of the processing beam (Para. 0089, “For example, such adjustment may be carried out automatically, to adjust the imaging beam for changes in the velocity of the processing beam, and/or changes in the direction of the processing beam, and/or changes in the relative velocity between the beam delivery system and the workpiece, and/or changes in the process beam velocity and/or the velocity of the process beam's focus relative to the workpiece.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the system in modified Schoenleber to include the feature as taught by Webster.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of allowing the interferometer to compensate for motion and misalignment, which can improve the measuring capabilities of the system, as stated by Webster, Para. 0089, “imaging beam's position relative to the processing beam, to compensate for motion/misalignment”.
Claims 12-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar) in further view of Tanaka (WO 2019194188 A1).
Regarding claim 12, modified Schoenleber teaches the method according to claim 1, as set forth above.
Modified Schoenleber does not disclose:
wherein the measurement optical path and the reference optical path include corresponding optical elements, the reference optical path including a reflective return element corresponding to the surface of the material interposed in the measurement optical path, and optical attenuator means configured to balance an intensity of reference optical radiation reflected by said reflective return element with respect to the intensity of measurement optical radiation reflected by the material being processed.
However, Tanaka discloses, in the similar field of interferometers (Page 2, Para. 2 from end, “principle of a Michelson interferometer.”), where a measurement optical path and a reference optical path include different optical paths (Page 4, Para. 4, “measurement laser light L1”, and Page 4, Para. 5, “reference laser light L2”, where Fig. 1 shows that the two paths L1 and L2 include different elements), where an optical attenuator can be used to balance an intensity of reference optical radiation (Page 7, Para. 2 from end, “In this way, for the optical attenuator G to be the reference, the set value of the optical attenuator G is obtained using the reference light measuring device PD and the laser light source 2 equivalent to the reflected light measuring device 1. Obtain characteristic data of the relationship of attenuation.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference optical beam in modified Schoenleber to include an optical attenuator as taught by Tanaka.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to adjust for reflectance values between the optical fiber and air, where the optical attenuator can assist with calibrating the reference beam, as stated by Tanaka, Page 8, Para. 6, “In the reference setting process of the reflected light amount, the optical attenuator is set so that the light amount received by the calibration reflection measuring device S becomes −14.7 dB, which is the reflectance between the cut surface of a typical optical fiber and air. Adjust the set value of G. Then, the set value of the optical attenuator G at this time is stored as the set value g from which the reference reflected light amount value −14.7 dB is obtained”.
Regarding claim 13, modified Schoenleber teaches the method according to claim 12, as set forth above, discloses wherein said measurement optical path and said reference optical path originate from a common source, are separated by beam splitters, led separately to the surface of the material being processed and to said reflective return element, respectively, (Schoenleber, Para. 0031, “The branching-off may be effected by means of a beam splitter of any type. In the most simple case, the branching-off is effected in such a manner that an optical element such as, for example, a mirror or a refractive element is arranged in the beam path of the object light such that two differing light paths are produced.”, and Para. 0032, “In the case of another embodiment, the measuring beam is the reference beam of the coherence tomograph.”).
Modified Schoenleber does not disclose:
gathered in a detection optical path, in the detection optical path the measurement beam being separated from the reference beam, said measurement and reference beams being directed with controllable orientation towards said common region of incidence of the optical interferometric sensor arrangement, the controllable orientation determining the angle of incidence between the measurement beam and the reference beam.
However, Otomo discloses where the reference and measurement beams can have controllable orientations towards the sensor arrangement (Page 4, Para. 4, “an incident optical path, a measurement optical path, a reference optical path, and a detection optical path are provided along a cross shape around the beam splitter, and an optical path difference is provided between the reference optical path and the measurement optical path. In addition, the reference mirror is tilted by a minute amount (fixed or tilted) to form interference fringes on the detection means. Thereby, it is possible to obtain an interference image in the height direction of the sample in one shot without scanning the laser beam.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the reference and measurement beams in modified Schoenleber to include controllable orientation as taught by Otomo.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to obtain interference fringes without needing to scan the laser beam across the surface, as stated by Otomo, Page 4, Para. 4, “In addition, the reference mirror is tilted by a minute amount (fixed or tilted) to form interference fringes on the detection means. Thereby, it is possible to obtain an interference image in the height direction of the sample in one shot without scanning the laser beam.”.
Claims 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar) in further view of Medower et al. (US 20070211256 A1, hereinafter Medower).
Regarding claim 16, modified Schoenleber teaches the method according to claim 1, as set forth above.
Modified Schoenleber does not disclose:
wherein the determination of the difference in optical length between the measurement optical path and the reference optical path is based on a normalized optical length of the measurement optical path which is calculated starting from a normalized geometric length and from a refractive index of a material transmission medium of a portion of said measurement optical path, in which the normalized geometric length is calculated as a function of a mechanical deformation of said material transmission medium according to a predetermined nominal relationship of dependence of geometric length upon the mechanical deformation of the material transmission medium of the measurement beam.
However, Medower discloses, in the similar field of interferometers (Para. 0003, “The present invention relates to interferometry.”), where optical paths can take into account mechanical deformation (Para. 0068, “Strain sensors are useful in measuring, for example, small deformations of an object due to acoustical, mechanical or thermal stress. The illumination unit 54 and a corresponding expansion lens 92 are adapted so that they may be positioned at an arbitrary angle y relative to the normal (z axis) to the test object 62 and adjust the illumination to fill the area of interest. Imaging lens 96 is used to collect light scattered from the test object 62 and produce an image at the LCPM 14 and detector array 14.”, where the strain sensors take into consideration mechanical deformations in order to adjust the illumination). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the interferometer in modified Schoenleber to include the strain sensor as taught by Medower.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to account for stress in changing the illumination of the interferometer, as stated by Medower, Para. 0068, “Strain sensors are useful in measuring, for example, small deformations of an object due to acoustical, mechanical or thermal stress. The illumination unit 54 and a corresponding expansion lens 92 are adapted so that they may be positioned at an arbitrary angle y relative to the normal (z axis) to the test object 62 and adjust the illumination to fill the area of interest.”.
Claims 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Schoenleber et al. (US 20160059350 A1, hereinafter Schoenleber) in view of Otomo et al. (JP 2010014426 A, hereinafter Otomo) and Korner et al. (EP 2843360 A1, hereinafter Korner) and Molnar et al. (DE 102010006749 A1, hereinafter Molnar) in further view of Kapit et al. (CA 2899651 A1, hereinafter Kapit).
Regarding claim 18, modified Schoenleber teaches the method according to claim 14, as set forth above.
Modified Schoenleber does not disclose:
wherein the pressure of the assist gas in the assist gas chamber of the nozzle is detected directly by pressure sensors facing said assist gas chamber.
However, Kapit discloses, in the similar field of interferometers (Para. 0002, “The present invention generally relates to interferometric measurements”), where pressure sensors can be used to detect the pressure within an assist gas chamber (Para. 0083, “a transducer 702 (such a pressure, temperature, salinity, sensor) may sense a condition ( e.g., salinity, pressure, temperature, strain, vibration, distance, refractive index of a medium, and changes thereof) of an environment 704. In response, the transducer 702 may alter either a physical path or radiation, a refractive index, or both.”). It would have been obvious for one of ordinary skill in the art before the effective filling date of the claimed invention to have modified the system in modified Schoenleber to include pressure sensors as taught by Kapit.
One of ordinary skill in the art would have been motivated to make this modification in order to gain the advantage of being able to directly determine pressure in order to allow the interferometer to change optical paths in order to compensate for pressure changes, as stated by Kapit, Para. 0083, “a transducer 702 (such a pressure, temperature, salinity, sensor) may sense a condition ( e.g., salinity, pressure, temperature, strain, vibration, distance, refractive index of a medium, and changes thereof) of an environment 704. In response, the transducer 702 may alter either a physical path or radiation, a refractive index, or both.”.
Conclusion
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/KEVIN GUANHUA WEN/Examiner, Art Unit 3761
05/29/2026
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