Prosecution Insights
Last updated: April 19, 2026
Application No. 17/379,492

OPTICAL PROXIMITY SYSTEM

Final Rejection §103
Filed
Jul 19, 2021
Examiner
CHILTON, CLARA GRACE
Art Unit
3645
Tech Center
3600 — Transportation & Electronic Commerce
Assignee
Northrop Grumman Systems Corporation
OA Round
4 (Final)
56%
Grant Probability
Moderate
5-6
OA Rounds
3y 12m
To Grant
67%
With Interview

Examiner Intelligence

Grants 56% of resolved cases
56%
Career Allow Rate
31 granted / 55 resolved
+4.4% vs TC avg
Moderate +11% lift
Without
With
+10.6%
Interview Lift
resolved cases with interview
Typical timeline
3y 12m
Avg Prosecution
43 currently pending
Career history
98
Total Applications
across all art units

Statute-Specific Performance

§101
1.4%
-38.6% vs TC avg
§103
58.1%
+18.1% vs TC avg
§102
23.4%
-16.6% vs TC avg
§112
15.6%
-24.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 55 resolved cases

Office Action

§103
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 . Response to Arguments Applicant's arguments filed 01/05/2026 have been fully considered but they are not persuasive. Applicant argues neither Kakuma or Dandliker teach a moving target as they do not have a cavity with a changing length, and that Oh does not teach calculating the distance to the object and determining relative movement. While examiner agrees Kakuma and Dandliker don't teach a cavity with changing length, examiner disagrees with argument regarding Oh. Oh teaches calculating an optical path length change between a moving reflector (metglass reflector) and a sensor. Thus, the target would be the metglass reflector. It is unclear from applicant's arguments where this differs from the claimed target object and distance calculation, as applicant simply states it is different. Thus, this argument is not persuasive. Regarding Claim 14, applicant argues none of the cited reference teach determining relative movement to position or couple the object and target objects to each other. Examiner respectfully disagrees. Applicant specifically argues against Christoffers. However, Christoffers was only used to teach a local oscillator. Further, Oh's calculation of changing distance would be sufficient to calculate 'relative movement' of the objects as the change of position is being measured. In response to applicant's argument that the cited references do not teach determining relative movement to position or couple the object and target objects to each other, a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim. Applicant argues Oh does not teach Claim 23, as Oh teaches a movable reflector inside the sensor, and not between the laser and a movable object. Examiner respectfully disagrees. Although it is true Oh teaches a reflector inside the sensor, there is nothing in the claims which requires the movable reflector to be outside the sensor. Thus, this argument is not persuasive. Applicant argues as Oh covers magnetic field measurement, one would not look to it to modify Kakuma and Dandlicker. Examiner respectfully disagrees. Although the end result of Oh's sensor is magnetic field measurement, it does so by measuring optical path length. Thus, it is in the field of laser sensors, which is the same as Kakuma and Dandlicker. Thus, this argument is not persuasive. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claims 1-6, 10-13, and 21-23 are rejected under 35 U.S.C. 103 as being unpatentable over Kakuma (Optical Review) in view of Dandliker (US 4907886 A), further in view of Oi (IEEE). Claim 1: Kakuma teaches an optical proximity sensor system comprising: a laser disposed on an object and being configured to generate an emitted optical beam at a linear polarization (pg. 511, second column) toward a moveable object (Fig 1, optical cavity), the target object configured to reflect a portion of the emitted optical beam thereby generating a reflected optical beam (Fig 1 and pg. 511, second column); A first photodetector (Fig. 1, APD1) configured to receive the diverted portion of the emitted optical beam and to generate a first proximity signal having a first frequency that is indicative of the distance to the […] target object based on the diverted portion of the emitted optical beam (Fig. 2, output of APD1, APD2), A second photodetector (Fig 1, APD2) configured to receive the diverted portion of the reflected optical beam and to generate a second proximity signal having a second frequency that is indicative of the distance to the […] target object based on the diverted portion of the reflected optical beam (Fig. 2, output of APD1, APD2), and a proximity processor configured to calculate the distance to the target object to position or couple the object and the moveable target object to one another (intended use – any measure of distance could be used to ‘position or couple’ – i.e.: determining relative position) based on the first frequency of the first proximity signal and the second frequency of the second proximity signal (Pg. 512, highlighted portion). Kakuma does not teach a first partially reflective mirror configured to divert a portion of the emitted optical beam; a second partially reflective mirror configured to divert a portion of the reflected optical beam. Dandliker teaches an interferometer which uses two photodetectors (Fig 1, photodetectors 35 and 45). Light is input to each photodetector via a half mirror (Fig 1, half mirrors 30 and 40) and a polarizer (Fig 1, polarizers 34 and 44 and Col 3, line 57 – Col 4 line 14). It would have been obvious before the priority date to use the two photodetectors with separate polarizers and mirrors as taught by Dandliker instead of Kakuma’s single half mirror and polarizer because this allows for further separation of the two light beams, allowing individual refinement of each light beam. Further, this falls under the KSR rational of a simple substitution of one known element (a single half mirror and polarizer leading to two detectors) for another (separate half mirrors and polarizers for each polarizer) to yield predictable results. Kakuma, as modified in view of Dandliker, does not teach, but Ooi does teach, the optical cavity having a changing length and the target object being movable (pg. 1, under "Sensor Fabrication" - using Metglas reflector as "object"), and a proximity processor […] determining relative movement between the target object and the laser (Fig. 3(b), output signals and pg. 1, under "Sensor Fabrication" - air gap length change detected via phase difference and intensity modulation). It would have been obvious before the effective filing date to use the Metglas reflector, as taught by Ooi, in the system as taught by Kakuma, as modified in view of Ooi, because a Metglas reflector is known in the art (and sold online). In addition, as Oh teaches, this allows for simple sensor geometry for sensing magnetic fields (See Introduction). Claim 2: Kakuma, as modified in view of Dandliker and Oi, teaches the further comprising a first linear polarizer configured to pass a first linear polarization and to block a second linear polarization of the diverted portion of the emitted optical beam from the first partially reflective mirror to the first photodetector to generate the first proximity signal as a first pulsed signal having the first frequency and a second linear polarizer configured to pass the first linear polarization and to block the second linear polarization of the diverted portion of the reflected optical beam from the second partially reflective mirror to the second photodetector to generate the second proximity signal as a second pulsed signal having the second frequency (Dandliker Fig 1, half mirrors 30 and 40 and polarizers 34 and 44 and Col 3, line 57 – Col 4 line 14). Claim 3: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 2, further comprising a quarter-wave plate arranged between the laser and the movable target object and configured to convert the emitted optical beam from the first linear polarization to a circular-polarization (Kakuma Fig 1, QWP) and to convert the reflected optical beam from the circular-polarization to the second linear polarization (Kakuma Fig 1, QWP), and is further configured to convert the emitted optical beam from the second linear polarization to the circular-polarization and to convert the reflected optical beam from the circular-polarization to the first linear polarization (Kakuma pg. 511 first column, describing switching). Claim 4: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 3, wherein the laser is configured as a vertical-cavity surface-emitting laser (VCSEL) configured to oscillate between generating the emitted optical beam at the first linear polarization and generating the emitted optical beam at the second linear polarization in response to the VCSEL receiving the reflected optical beam (Kakuma pg. 511 first column – describing switching). Claim 5: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 4, further comprising a collimating lens that aligns the emitted optical beam thereby narrowing a spatial cross section of the emitted optical beam to allow more optical energy from the reflected optical beam to re-enter the VCSEL (Kakuma Fig 1, CL). Claim 6: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 4, wherein the second frequency of the second proximity signal corresponds to periodic transitions of the oscillation between the first linear polarization and the second linear polarization of the reflected optical beam (Kakuma pg. 511, switching frequency), and wherein the proximity processor is configured to calculate the distance to the movable target object based on the second frequency of the periodic transitions of the second proximity signal (Kakuma pg. 512, highlighted portion). Claim 10: Claim 10 is a method claim corresponding to Claim 1. Thus, see rejection above. Claim 11: Kakuma, as modified in view of Dandliker and Oi, teaches the method of claim 10, wherein generating the emitted optical beam comprises periodically switching the linear polarization of the emitted optical beam between a first linear polarization and a second linear polarization (Kakuma pg. 511, switching frequency). Claim 12: Kakuma, as modified in view of Dandliker and Oi, teaches the method of claim 11, wherein the laser is a VCSEL and wherein the periodic switching is based on providing the reflected optical beam to the VCSEL (Kakuma pg. 511 first column, VCSEL). Claim 13: Kakuma, as modified in view of Dandliker and Oi, teaches the method of claim 11, wherein generating the first proximity signal and the second proximity signal comprises generating the first proximity signal and the second proximity signal such that the first frequency of the first proximity signal and the second frequency of the second proximity signal are based on a frequency of a periodic switching of the linear polarization of the emitted optical beam between a first linear polarization and a second linear polarization. (Kakuma pg. 511 column 1, switching frequency). Claim 21: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 1, but not wherein the wherein the emitted optical beam has one of a parallel or a perpendicular linear polarization, and the reflected optical beam as the other of the parallel or the perpendicular linear polarization opposite the emitted optical beam. However, Dandliker teaches that the two polarizers (Fig 1, 34 and 44) are arranged at 45 degree angles with respect to each polarization of the light beam (Col. 4, lines 27-24 – obvious that this implies two different perpendicular polarizations). It would have been obvious before the priority date to use the two perpendicular polarizations, as taught by Dandliker, with the optical proximity sensor as taught by Kakuma, as modified in view of Dandliker and Oi, because this allows for better differentiation of the two light beams. Claim 22: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 21, wherein the first photodetector is configured to generate the first proximity signal having the first frequency based on a frequency of periodic oscillation of the emitted optical beam between the parallel and the perpendicular linear polarization, wherein the second photodetector is configured to generate the second proximity signal having the second frequency based on a frequency of periodic oscillation of the reflected optical beam between the parallel and the perpendicular linear polarization (Kakuma Fig. 2, output of APD1, APD2). Claim 23: Kakuma, as modified, teaches the optical proximity sensor of claim 21, further comprising an optical cavity system comprising an optical cavity, the optical cavity having a changing length defined by a distance between the laser and the moveable target object (Kakuma Fig. 1, optical cavity, along with Oi’s metglass reflector). Claims 7, 14, 15, and 18-20 are rejected under 35 U.S.C. 103 as being unpatentable over Kakuma (Optical Review) in view of Dandliker (US 4907886 A), further in view of Oi (IEEE), further in view of Christoffers (US 20200124712 A1). Claim 7: Kakuma, as modified in view of Dandliker and Oi, teaches the optical proximity sensor system of claim 4, but not further comprising a local oscillator configured to generate a reference frequency signal, wherein the proximity processor is configured to determine the distance to the movable target object based on a comparison between the reference frequency signal and the proximity signal. Although Dandliker does teach a reference signal (Fig. 1, reference photodetector 35), this is not explicitly a local oscillator. Christoffers teaches a signal modulation device which includes a local oscillator (Fig 1, LO 102) configured to provide a reference frequency (Fig 1, reference frequency 104 and [0020]). It would have been obvious before the priority date to use the local oscillator as taught by Christoffers to provide the frequency signal as taught by Kakuma, as modified in view of Dandliker and Oi, because using a local oscillator to provide a reference frequency is well-known in the art, as local oscillators provide a frequency internal to the system, and thus easily controlled. Claim 14: Kakuma teaches an optical proximity sensor system comprising: […] an optical proximity detection system comprising: a laser disposed on an object and being configured to generate an emitted optical beam toward a […] target object (Fig. 1) at a linear polarization that periodically transitions between a first linear polarization and a second linear polarization in response to a reflected optical beam (pg. 511, VCSEL switching polarization in response to received signal); the […] target object configured to reflect the emitted optical beam thereby generating the reflected optical beam (Fig 1, CC); a quarter-wave plate arranged between the laser and the […] target object and configured to convert the emitted optical beam from the first linear polarization to a circular-polarization and to convert the reflected optical beam from the circular- polarization to the second linear polarization (Fig 1, QWP and pg. 511); and is further configured to convert the emitted optical beam from the second linear polarization to the circular- polarization and to convert the reflected optical beam from the circular- polarization to the first linear polarization (pg. 511 – describing QWP operation taken with pg. 511 – describing switching), and to generate a proximity signal that is indicative of the distance to the target object based on the diverted portion of the at least one of the emitted optical beam and the reflected optical beam (Fig 2, showing output of spectrum analyzer and frequency counter); and a proximity processor configured to calculate the distance to the […] target object and to determine relative movement between the object and the […] target object to position or couple the object and the moveable target object to one another (intended use – any measure of distance could be used to ‘position or couple’ – i.e.: determining relative position) based on a comparison of the reference signal and the proximity signal (pg. 512, finding L based on waveform). Kakuma does not teach a local oscillator configured to generate a reference signal; a first partially reflective mirror configured to divert a portion of the emitted optical beam; A second partially reflective mirror configured to divert a portion of the reflected optical beam; and a first photodetector configured to receive the diverted portion of the emitted optical beam and to generate a first proximity signal having a first frequency that is indicative of the distance to the target object based on the diverted portion the emitted optical beam; a second photodetector configured to receive the diverted portion of the reflected optical beam and to generate a second proximity signal having a first frequency that is indicative of the distance to the target object based on the diverted portion the reflected optical beam; Dandliker teaches an interferometer which uses two photodetectors (Fig 1, photodetectors 35 and 45). Light is input to each photodetector via a half mirror (Fig 1, half mirrors 30 and 40) and a polarizer (Fig 1, polarizers 34 and 44 and Col 3, line 57 – Col 4 line 14). One photodetector detects reference light and the other measurement light (Col 3, lines 64-68). Both signals are used to determine a final result (Col 6 line 35 – Col 7, line 18). It would have been obvious before the priority date to use the two photodetectors with separate polarizers and mirrors as taught by Dandliker instead of Kakuma’s single half mirror and polarizer because this allows for further separation of the two light beams, allowing individual refinement of each light beam. Further, this falls under the KSR rational of a simple substitution of one known element (a single half mirror and polarizer leading to two detectors) for another (separate half mirrors and polarizers for each polarizer) to yield predictable results. Kakuma, as modified in view of Dandliker, does not teach, but Ooi does teach, the optical cavity having a changing length and the target object being movable (pg. 1, under "Sensor Fabrication" - using Metglas reflector as "object"), and a proximity processor […] determining relative movement between the target object and the laser (Fig. 3(b), output signals and pg. 1, under "Sensor Fabrication" - air gap length change detected via phase difference and intensity modulation). It would have been obvious before the effective filing date to use the Metglas reflector, as taught by Ooi, in the system as taught by Kakuma, as modified in view of Ooi, because a Metglas reflector is known in the art (and sold online). In addition, as Oh teaches, this allows for simple sensor geometry for sensing magnetic fields (See Introduction). None of Kakuma, Dandliker, or Oi teach using a local oscillator for the frequency signal. Christoffers teaches a signal modulation device which includes a local oscillator (Fig 1, LO 102) configured to provide a reference frequency (Fig 1, reference frequency 104 and [0020]). It would have been obvious before the priority date to use the local oscillator as taught by Christoffers to provide the frequency signal as taught by Kakuma, as modified in view of Dandliker and Ooi, because using a local oscillator to provide a reference frequency is well-known in the art, as local oscillators provide a frequency internal to the system, and thus easily controlled. Claim 15: Kakuma, as modified in view of Dandliker, Oi, and Christoffers, teaches the a first linear polarizer configured to pass the first linear polarization and to block the second linear polarization of the diverted portion of the emitted optical beam from the first partially reflective mirror to the first photodetector to generate the first proximity signal as a first pulsed signal (Dandliker Fig. 1, half mirror 30), And a second linear polarizer configured to pass the second linear polarization and to block the second linear polarization of the diverted portion of the reflected optical beam from the second partially reflective mirror to the second photodetector to generate the second proximity signal as a second pulsed signal having the second intensity (Dandliker Fig. 1, half mirror 40). Claim 18: Kakuma, as modified in view of Dandliker, Oi, and Christoffers, teaches the optical proximity sensor system of claim 14, wherein the second frequency of the second proximity signal corresponds to the periodic transitions of the oscillation between the first linear polarization and the second linear polarization of the reflected optical beam (Kakuma pg. 511, switching frequency). and wherein the proximity processor is configured to calculate the distance to the movable target object based on the second frequency of the periodic transitions of the second proximity signal (Kakuma pg. 511, f = c/(4L) equation). Claim 19: Kakuma, as modified in view of Dandliker, Oi, and Christoffers, teaches the optical proximity sensor system of claim 14, wherein the laser is configured as a vertical-cavity surface-emitting laser (VCSEL) configured to oscillate between generating the emitted optical beam at the first linear polarization and generating the emitted optical beam at the second linear polarization in response to the VCSEL receiving the reflected optical beam (Kakuma pg. 511, describing polarization mode switching of VCSELs). Claim 20: Kakuma, as modified in view of Dandliker, Oi, and Christoffers, teaches the optical proximity sensor system of claim 19, further comprising a collimating lens that aligns the emitted optical beam thereby narrowing a spatial cross section of the emitted optical beam to allow more optical energy from the reflected optical beam to re-enter the VCSEL (Kakuma Fig 1, lens CL). Conclusion THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to CLARA CHILTON whose telephone number is (703)756-1080. The examiner can normally be reached Monday-Friday 6-2 MT. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Helal Algahaim can be reached at 571-270-5227. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /CLARA G CHILTON/Examiner, Art Unit 3645 /HELAL A ALGAHAIM/SPE , Art Unit 3645
Read full office action

Prosecution Timeline

Jul 19, 2021
Application Filed
Feb 26, 2025
Non-Final Rejection — §103
May 29, 2025
Applicant Interview (Telephonic)
May 29, 2025
Examiner Interview Summary
Jun 16, 2025
Response Filed
Jul 07, 2025
Final Rejection — §103
Sep 09, 2025
Request for Continued Examination
Oct 01, 2025
Response after Non-Final Action
Oct 02, 2025
Non-Final Rejection — §103
Dec 22, 2025
Examiner Interview Summary
Dec 22, 2025
Applicant Interview (Telephonic)
Jan 05, 2026
Response Filed
Feb 24, 2026
Final Rejection — §103 (current)

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Prosecution Projections

5-6
Expected OA Rounds
56%
Grant Probability
67%
With Interview (+10.6%)
3y 12m
Median Time to Grant
High
PTA Risk
Based on 55 resolved cases by this examiner. Grant probability derived from career allow rate.

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