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 .
This is the first office action on the merits and is responsive to the papers filed 04/05/2023. Claims 1-19, 22 are currently pending and examined below.
Information Disclosure Statement
The information disclosure statements submitted by Applicant are in compliance with the provision of 37 CFR 1.97, 1.98 and MPEP § 609. They have been placed in the application file and the information referred to therein has been considered as to the merits.
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, 3, 5, 7, 8, 9, 10, 16-19, 22 are rejected under 35 U.S.C. 103 as being unpatentable over Ohtomo et al. (US 20070263202 A1, “Ohtomo”) in view Maleki et al. (US 20190154835 A1, “Maleki”).
Regarding claim 1, Ohtomo teaches an optical distance measurement device (Para 2) comprising:
a light transmitter (Para 1, 8, 33, light emitting element 1) configured to transmit distance measurement light (Para 30, distance measuring light 22) to a measurement object (Para 30, objects 16);
a light receiver (Fig. 3, para 57, 61-62, lens 48) configured to receive reflected light being reflected from the measurement object by the transmitted distance measurement light;
a modulator (para71, control computation unit 15) configured to generate reference light acquired by performing intensity modulation on a light source according to a distance measurement range (para 67 and 71: “selecting a Ref internal reference light corresponding to the light quantity of the reflected distance measurement light 22'" so as to change the "light quantity variation of the internal reference light 22'" so as to “equal the change in the light quantity of the reflected distance measurement light 22' from a measurement object at a close distance and the light quantity of the reflected distance measurement light 22' from a measurement object at a long distance") ;
a detector configured to generate a reception signal by causing the received reflected light and the generated reference light (Para 61-62 and 64) (to interfere with each other); and
a distance calculator (control computation unit 15) configured to calculate a distance to the measurement object, based on the transmitted distance measurement light and the generated reception signal (Para 64. See also, para 14).
Ohtomo fails to explicitly teach but Maleki teaches that the detector configured to generate a reception signal by causing the received reflected light and the generated reference to interfere with each other (Para 121).
It would have been obvious to one of ordinary skill in the art to modify Ohtomo’s distance measuring device to employ Maleki’s detector. Doing so will improve sensitivity and phase accuracy in optical distance measurement systems. Applying Maleki’s coherent detection to Ohtomo’s system would have predictably improved measurement robustness and accuracy, particularly for weak reflected signals.
Regarding claim 3, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 1, wherein the reference light has intensity in a specific distance measurement range, that is stronger than intensity in another distance measurement range (Ohtomo, Para 67, The amount of the light amount change of the internal reference light 22'' is set in such manner that it is equal to or more than the change of the light amount of the reflected distance measuring light 22' from the object to be measured at near distance and the light amount of the reflected distance measuring light 22' from the object to be measured at long distance. More concretely, the light amount change of the internal reference light 22'' should be set to the maximum value in the dynamic range of the photodetection unit or within the dynamic range. See also, para 68-69, reference signal is divided to levels … L1, L2, L3, L4, L5 and para 71, selects an internal reference standard to match the light amount).
Regarding claim 5, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 1, wherein intensity of the reference light changes to a pulse shape.
Maleki teaches that the reference light has a pulse shape, because Maleki explicitly discloses generating a “pulsed series of optical chirps” (Para 51-52, Fig. 8).
Maleki further teaches that each optical chirp generated by the laser serves as a local oscillator (LO) reference chirp when combined with reflected light at the photodetector (Para 120-121). Accordingly, the intensity of the reference light varies in time as a pulse shape corresponding to the pulsed optical chirps.
It would have been obvious to one of ordinary skill in the art to configure the reference light to have a pulse shape, as taught by Maleki, because using pulsed optical chirps in a coherent optical distance measurement system improves signal-to-noise ratio, reduces interference from out-of-range reflections, and enables controlled timing alignment between transmitted and reference signals. Applying such pulsed operation to the reference light—generated from the same coherent light source as the transmitted signal—represents a predictable use of a known technique to achieve improved measurement robustness and processing efficiency without changing the fundamental operation of the optical interference-based distance measurement system.
Regarding claim 7, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 5, wherein
the light transmitter repeatedly transmits the distance measurement light at a predetermined distance measurement period (Ohtomo teaches repeated projection of distance measuring light during rotary irradiation/scanning (Para 30 and 58) under a controlled measurement sequence (Para 53-54), and the modulator generates the reference light for each of the distance measurement periods (Ohtomo teaches a modulated distance-measuring light (Para 3, 57) and that during each scanning/measurement cycle, internal reference light is obtained from that distance measuring light as it traverses the reference reflection prism (Para 62) and is used with reflected distance-measuring light to compute distance (Para 64.).
Regarding claim 8, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 7, wherein the modulator generates the reference light in the distance measurement range in which a distance from the optical distance measurement device is different, for each of the distance measurement periods (Ohtomo, "a Ref internal reference light corresponding to the light quantity of the reflected distance measurement light 22' is selected" so as to change the "light quantity variation of the internal reference light 22'" so as to "equal the change in the light quantity of the reflected distance measurement light 22' from a measurement object at a close distance and the light quantity of the reflected distance measurement light 22' from a measurement object at a long distance" (paragraphs 67 and 71),).
Regarding claim 9, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 8, wherein the modulator generates the reference light in generation order in such a way that the distance measurement range becomes far from the optical distance measurement device or the distance measurement range becomes close to the optical distance measurement device (Ohtomo teaches generating internal reference light sequentially during a distance-measurement operation as the distance measuring light is projected by rotary irradiation or scanning (Para 66). Specifically, each time the distance measuring light traverses the reference reflection prism during scanning, the light is reflected and received as internal reference light (Para 62). Ohtomo further teaches configuring the internal reference light such that its light amount corresponds to distance measurement ranges including near distance and long distance targets, by setting the variation range of the internal reference light to cover changes in reflected signal strength for both near and far objects (Para 67). Accordingly, as the scanning operation proceeds, the internal reference light is generated in a temporal (generation) order corresponding to distance measurement ranges becoming closer to or farther from the optical distance measurement device, as recited in claim 9.).
Regarding claim 10, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 9, wherein the modulator generates the reference light in such a way that the distance measurement ranges in reference light before and after in the generation order overlap with each other (As discussed in claim 9, Ohtomo teaches generating internal reference light sequentially during scanning as the distance measuring light traverses a reference reflection prism (Para 62, 66). Ohtomo further teaches that the internal reference light intensity is varied continuously by an amplitude filter whose density gradually changes as the distance measuring light traverses the reference reflection prism (Para 42 and 67). Because the internal reference light varies continuously and is generated sequentially in time, reference light generated immediately before and after in the generation order necessarily corresponds to overlapping distance measurement ranges rather than discrete, non-overlapping ranges. Therefore, Ohtomo teaches generating the reference light such that distance measurement ranges in reference light before and after in the generation order overlap with each other, as recited in claim 10.).
Regarding claim 16, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 1, wherein intensity of the reference light continuously changes according to the distance measurement range (Ohtomo, para 42 “density is continuously changed” and para 67 “light amount … is gradually changed”).
Regarding claim 17, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 16, wherein intensity of the reference light changes to a linear taper shape (Ohtomo, para 42, density is continuously changed … transmitting light amount is continuously decreased or continuously increased. A continuously changing density corresponds to a linear (or near-linear) taper).
Regarding claim 18, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 17, wherein intensity of the reference light changes in proportion to a distance from the optical distance measurement device (Ohtomo, para 62, 66, Reference prism traversed during distance-measuring scan (Reference light intensity varies as a function of traversal position during scanning) and para 67, …set to cover … near distance and … long distance (Intensity variation is explicitly set to cover near and far distances). Because scanning position corresponds to measurement distance, and reference intensity is varied continuously across traversal, intensity changes proportionally with distance.).
Regarding claim 19, Ohtomo, in view of Maleki, teaches the optical distance measurement device according to claim 16, wherein intensity of the reference light changes to a curved taper shape (Ohtomo, Para 42, density may be changed stepwise so far as density is substantially and gradually changed. A stepwise or non-uniform density profile corresponds to a curved (non-linear) taper).
Claim 22 is a method claim corresponding to system claim 1. It is rejected for the same reason.
Claims 2, 11-14 are rejected under 35 U.S.C. 103 as being unpatentable over Ohtomo in view Maleki and Sadao Yamashita (US 20020154051 A1).
Regarding claim 2, Ohtomo, in view of Maleki, fails to explicitly teach the optical distance measurement device according to claim 1, wherein the reference light has intensity in a case where the distance measurement range is far from the optical distance measurement device, that is stronger than intensity in a case where the distance measurement range is close to the optical distance measurement device. However, Yamashita teaches that received signal strength decreases rapidly with distance (1/R⁴) and that system amplitude/gain must be increased for far distances and reduced for near distances to prevent saturation and maintain sensitivity (Para 4-7, 11, 45).
It would have been obvious to one of ordinary skill in the art to configure the reference light in Ohtomo to be stronger for far distance measurement ranges than for close distance ranges, as taught by Yamashita, in order to compensate for reduced return strength at longer distances and avoid saturation at shorter distances.
Regarding claim 11, Ohtomo, in view of Maleki, fails to explicitly teach the optical distance measurement device according to claim 7, wherein intensity of the reference light is different for each of the distance measurement periods. However, Yamashita teaches that amplitude/gain is varied in accordance with distance, which in FMCW systems is determined per modulation cycle (per measurement period) via beat frequency (Para 11, 47-53, 60).
Regarding claim 12, Ohtomo, in view of Maleki, fails to explicitly teach the optical distance measurement device according to claim 7, wherein a width of the reference light varies according to the distance measurement range. However, Yamashita teaches varying signal processing bandwidth and weighting according to distance in order to optimize signal-to-noise ratio and avoid saturation (Para 11, 58-59),
It would have been obvious to one of ordinary skill in the art at the time of the invention to configure the reference light in Ohtomo in view of Yamashita such that its width varies according to the distance measurement range. Doing so, will optimize signal-to-noise ratio and avoid saturation.
Regarding claim 13, Ohtomo, in view of Maleki and Yamashita, teaches the optical distance measurement device according to claim 12, wherein the reference light has a width in a case where the distance measurement range is far from the optical distance measurement device, that is narrower than a width in a case where the distance measurement range is close to the optical distance measurement device (Yamashita, Para 7, 11, 59, teaches that far-distance signals require tighter signal conditioning than near-distance signals. Applying narrower reference-light widths for far distance ranges than for close distance ranges would have been an obvious design choice to improve detection reliability at long distances while avoiding saturation at short distances.).
Regarding claim 14, Ohtomo, in view of Maleki and Yamashita, teaches the optical distance measurement device according to claim 12, wherein the reference light has a width in a specific distance measurement range, that is narrower than a width in another distance measurement range (Yamashita, Para 7, 11, 59, teaches that far-distance signals require tighter signal conditioning than near-distance signals. Applying narrower reference-light widths for far distance ranges than for close distance ranges would have been an obvious design choice to improve detection reliability at long distances while avoiding saturation at short distances,).
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Ohtomo in view Maleki and Garry N. Link (US 5850409 A, “Link”).
Regarding claim 4, Ohtomo, in view of Maleki, fails to explicitly teach but Link teaches the optical distance measurement device according to claim 1, wherein average power of the reference light is the same as power of a light source before performing the intensity modulation (col 2: lines 7-8, col 3: lines 34-39; claim 7 “controlling the first current to provide a predetermined average optical signal from the laser”).
It would have been obvious to incorporate a known constant-average-power laser modulation technique into the Ohtomo, because maintaining constant average optical power during intensity modulation is a recognized requirement in coherent optical distance measurement systems to stabilize detector bias, preserve interference accuracy, and prevent measurement error. Such integration represents a routine design optimization yielding predictable improvements in stability and accuracy.
Claims 6, 15 are rejected under 35 U.S.C. 103 as being unpatentable over Ohtomo in view Maleki and Hartog (US 20130113629 A1, “Hartog”).
Regarding claim 6, Ohtomo, in view of Maleki, fails to explicitly teach the optical distance measurement device according to claim 5, wherein a width of the reference light is wider than a width of the distance measurement light.
However, Hartog teaches that the distance-measurement light is generated by modulating an optical signal to form a pulse that is launched into the sensing fiber, the pulse having a finite temporal duration (Para 44; see also example pulse duration in (Para 69). The reference further teaches that the reference (local oscillator) light used for coherent detection is continuous light coming directly from the optical source and is not pulsed (Para 43–44 and 82). Because the reference light is continuous while the distance-measurement light is a finite-duration pulse, the temporal width of the reference light is wider than the temporal width of the distance-measurement light, as recited in claim 6.
It would have been obvious to one of ordinary skill in the art at the time of the invention to apply the pulse-versus-continuous reference configuration taught by Hartog to the optical distance measurement device of Ohtomo in order to improve signal-to-noise ratio, stabilize interference detection, and enable reliable coherent mixing across the full measurement window, particularly where reflected measurement signals are temporally limited.
Regarding claim 15, Ohtomo, in view of Maleki, fails to explicitly teach the optical distance measurement device according to claim 7, wherein the modulator generates a plurality of beams of the reference light for each of the distance measurement periods.
However, Hartog teaches an optical modulator configured to generate a plurality of reference (local oscillator) optical signals by producing multiple modulation sidebands from a light source, which are used concurrently during a single measurement cycle for coherent detection (Para 129-131, para 135-136, Fig. 25). It would have been obvious to one of ordinary skill in the art to modify Ohtomo’s reference-light generation to produce a plurality of reference light beams as taught by Hartog, since Ohtomo already relies on reference light for distance calculation and Hartog demonstrates that multiple reference beams improve signal robustness, noise tolerance, and measurement reliability during a measurement period. Such a modification represents a predictable use of known modulation techniques to improve the performance of Ohtomo’s distance measurement system.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Imaki et al. (US 9618530 B2), teaches Laser Radar Device
Ando et al. (US 20160291135 A1), teaches Laser radar device
Hui et al. (US 20080018881 A1), teaches Coherent Detection Scheme for FM Chirped Laser Radar
LaChapelle et al. (US 20210055387 A1), teaches coherent pulsed lidar system
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/JEMPSON NOEL/Examiner, Art Unit 3645
/YUQING XIAO/Supervisory Patent Examiner, Art Unit 3645