JPWO2020216842A5 - - Google Patents

Claims (32)

An apparatus for managing coherent detection from multiple apertures in a lidar system, said apparatus comprising:
a first light source or port that provides a modulated illumination lightwave that illuminates a field of view;
a second light source or port providing a reference lightwave having a defined phase relationship to the modulated illumination lightwave;
An aperture array comprising a plurality of apertures arranged over one or more dimensions and configured to receive an optical wavefront comprising contributions to at least a portion of a field of view,
Each of two or more of said apertures is configured to receive a respective portion of said received optical wavefront, and at least two non-adjacent apertures in said aperture array contribute from the same portion of said field of view. configured to receive each portion of the received optical wavefront comprising
Each of the two or more apertures is coupled to a respective optical mixer that coherently interferes a respective portion of the received optical wavefront with a respective local oscillator lightwave, the respective local oscillator lightwave being , for each said opening, (i) between said second light source or port and each said light mixer, and (ii) between each said opening and each said light mixer, respectively. an array of apertures derived from the reference lightwave such that the difference in group delays of
A processing module configured to process electrical signals detected from the outputs of the optical mixers, wherein for each optical mixer of the plurality of optical mixers, at least one of the optical mixers determining at least one of phase or amplitude information from at least one electrical signal detected from the output;
determining a first direction-based information associated with a first subset of the field of view based on phase or amplitude information derived from at least two of the plurality of light mixers;
determining first distance information from the first direction-based information;
determining second direction-based information associated with a second subset of the field of view based on phase or amplitude information derived from at least two of the plurality of light mixers;
and determining second distance information from said second direction-based information. 2. The apparatus of claim 1, wherein the modulated illumination lightwave has a frequency spectrum including a peak at a frequency adjustable to provide a frequency modulated continuous wave (FMCW) illumination lightwave. 3. Apparatus according to claim 1 or 2, wherein the modulated illumination lightwave is a pulsed signal. 4. A device according to any one of the preceding claims, wherein the modulated illumination light wave is formed by alternating light of two wavelengths. 5. Apparatus according to any one of the preceding claims, wherein the modulated illumination lightwaves have spectra covering different frequency bands. Each of the group delay differences between (i) the second light source or port and the respective optical mixer and (ii) the respective aperture and the respective optical mixer is , corresponding to an optical path length difference of less than 10 cm. Each of the group delay differences between (i) the second light source or port and the respective optical mixer and (ii) between the respective aperture and the respective optical mixer is , corresponding to an optical path length difference of less than 1 cm. further processing the first direction-based information and the second direction-based information to obtain first and second intensities of light coming from the first and second subsets of the field of view, respectively; 8. Apparatus according to any one of claims 1 to 7, for measuring intensity respectively. further processing the first direction-based information and the second direction-based information to determine relative velocities of a plurality of objects reflecting light respectively coming from the first and second subsets of the field of view; 9. An apparatus according to any one of claims 1 to 8, which measures each of the . 10. Apparatus according to any one of the preceding claims, wherein at least part of the information based on the first direction and at least part of the information based on the second direction are determined in parallel. 11. Apparatus according to any one of the preceding claims, wherein the illumination light waves are provided to illuminate the entire field of view simultaneously. 11. Apparatus according to any one of the preceding claims, wherein the illumination light waves are provided for scanning different portions of the field of view over time. 13. Apparatus according to any one of the preceding claims, wherein one or more of the apertures of the aperture array are used to emit at least part of the illumination light wave. 14. Any one of claims 1 to 13, further comprising at least one illumination aperture not included in said aperture array, said illumination aperture configured to emit at least part of said illumination light wave. 3. Apparatus according to paragraph. 15. Apparatus according to any preceding claim, wherein the aperture array has its apertures arranged in a regularly spaced rectangular grid. 15. A device according to any preceding claim, wherein the array of apertures has its apertures arranged in a regularly spaced polar grid. 15. The apparatus of any one of claims 1-14, wherein the array of apertures has its apertures arranged in a Mills Cross configuration. 15. Apparatus according to any preceding claim, wherein the aperture array has its apertures arranged in a pseudo-random configuration. 19. Apparatus according to any preceding claim, wherein the array of apertures is defined by pixels of an imaging sensor. 20. Any of claims 1-19, wherein each said optical mixer is configured to provide in-phase/quadrature (IQ) detection by using a 90° shifted replica of said reference light wave. A device according to claim 1. 20. The optical mixer of claims 1-19, wherein each said optical mixer is configured to utilize interference with said reference lightwave in a multimode interferometric coupler to provide in-phase/quadrature (IQ) detection. A device according to any one of the preceding clauses. 22. Any one of claims 1 to 21, wherein the optical mixer is implemented through at least one of a partially transmissive layer, a directional coupler, an evanescent coupler, a multimode interference coupler, or a grating coupler. The apparatus described in . 3. The processing module is configured to compensate for errors in relative phase between apertures in the aperture array estimated based at least in part on a modulation pattern of the modulated illumination lightwave. 23. Apparatus according to any one of claims 1 to 22. The processing module is configured to compensate for errors in relative phase between apertures in the aperture array estimated based at least in part on calibration data obtained at a predetermined wavefront. 23. Apparatus according to any one of claims 1-22. The processing module compensates for errors in relative phase between apertures in the aperture array estimated using sensors that measure temperature and/or temperature gradients within the device and/or environment of the device. 23. Apparatus according to any one of the preceding claims, adapted to. 26. Apparatus according to any one of the preceding claims, wherein said processing module comprises an analog-to-digital conversion component. 27. Apparatus according to any preceding claim, wherein said processing module comprises a data serializer. 28. Apparatus according to any preceding claim, wherein the processing module comprises an electro-optical transducer for data output via a fiber optic link. 29. Apparatus according to any preceding claim, wherein the first light source or port and the second light source or port provide light from a single common light source. 30. Apparatus according to any one of the preceding claims, wherein said second light source or port provides light by phase modulation of light provided to said first light source or port. 31. Apparatus according to any one of the preceding claims, wherein said first light source or port illuminates said field of view via a light diffusing element. A method of managing coherent detection from multiple apertures, comprising:
providing a modulated illumination lightwave from a first light source or port to illuminate a field of view;
providing from a second light source or port a reference lightwave having a defined phase relationship with the modulated illumination lightwave;
receiving, at an aperture array comprising a plurality of apertures arranged over one or more dimensions, an optical wavefront comprising contributions over at least a portion of the field of view;
Each of two or more of said apertures is configured to receive a respective portion of said received optical wavefront, and at least two non-adjacent apertures in said aperture array contribute from the same portion of said field of view. configured to receive each portion of the received optical wavefront comprising
Each of the two or more apertures is coupled to a respective optical mixer that coherently interferes a respective portion of the received optical wavefront with a respective local oscillator lightwave, the respective local oscillator lightwave being , for each said opening, (i) between said second light source or port and each said light mixer, and (ii) between each said opening and each said light mixer, respectively. derived from the reference lightwave such that the difference in group delays of is substantially equal;
processing, in a processing module, electrical signals detected from the outputs of the optical mixers, the processing comprising: for each optical mixer of a plurality of the optical mixers, from the output of at least one of the optical mixers; determining at least one of phase or amplitude information from the at least one detected electrical signal;
determining a first direction-based information associated with a first subset of the field of view based on phase or amplitude information derived from at least two of the plurality of light mixers;
determining first distance information from the first direction-based information;
determining second direction-based information associated with a second subset of the field of view based on phase or amplitude information derived from at least two of the plurality of light mixers;
and determining second distance information from the second direction-based information.