LiDAR system and method
Disclosed are improved LiDAR systems and methods that achieve an improved signal-to-noise by interrogating a sub-region of a scene with an optical signal. An instantaneous field-of-view (FOV) of each detector pixel is narrowed along a first direction to reduce detection of solar-generated photons. Instantaneous FOVs of the pixels are compressed along the first direction to provide a composite FOV that is narrower than a total FOV. To sample the total FOV of a scene, the optical signal and composite FOV of the receiver are scanned across the scene along the first direction.
1. A LiDAR system comprising:
a transmitter operative for interrogating a sub-region of a scene with an optical signal, the scene being characterized by a total field-of view (TFOV) having a first lateral extent along a first direction and a second lateral extent along a second direction that is orthogonal to the first direction, and the optical signal having an illumination pattern having a first divergence in the first direction and a second divergence in the second direction, wherein the sub-region is characterized by a third lateral extent that is defined by the first divergence and a fourth lateral extent that is defined by the second divergence, wherein the fourth lateral extent is smaller than the second lateral;
a receiver operative for sampling the sub-region by detecting reflections of the optical signal that originate within the sub-region, the receiver including a focal-plane array (FPA) defined by a plurality of pixels that each have a single-photon detector, wherein the complete FPA is configured to image the sub-region with a composite field-of-view (CFOV) that matches the sub-region; and
a scanner operative for scanning the sub-region along the second direction such that the complete scene is interrogated with the optical signal and sampled by the complete FPA during a scan period.
2. The system according to claim 1 wherein the CFOV is gap free.
3. The system according to claim 1 further comprising a processor operative for receiving signals from the receiver during a scan period and integrating the signals.
4. The system according to claim 1 wherein the sub-region is smaller than the lateral extent of the scene in the first direction, and wherein the scanner is operative for scanning the sub-region along the first direction such that the complete TFOV is interrogated and sampled during a scan period.
5. The system according to claim 1 wherein the second angular range of IFOV is smaller than the first angular range of the IFOV.
6. The system according to claim 1 wherein the scanner is operative for scanning the sub-region along the second direction continuously.
7. The system according to claim 1 wherein the scanner is operative for scanning the sub-region along the second direction step-wise as a plurality of steps, and wherein the lateral extent of each step is matched to the lateral extent of the IFOV of a pixel.
8. A method of operating a LiDAR system comprising:
interrogating a sub-region of a scene with an optical signal, wherein the scene is characterized by a total field-of-view (TFOV) having a first lateral extent along a first direction and a second lateral extent along a second direction that is orthogonal to the first direction, and wherein the optical signal has an illumination pattern exhibiting a first divergence in the first direction and a second divergence in the second direction, the first divergence defining a third lateral extent of the sub-region and the second divergence defining a fourth lateral extent of the sub-region, wherein the fourth lateral extent is smaller than the second lateral extent;
sampling the sub-region by detecting reflections of the optical signal that originate within the sub-region, wherein the reflections are detected by a receiver including a plurality of pixels that each have a single-photon detector, and wherein each pixel exhibits an instantaneous field-of-view (IFOV) having a first angular range in the first direction and a second angular range in the second direction, and wherein the plurality of pixels are arranged such that they collectively define a focal-plane array (FPA) that is configured such that the complete FPA images the sub-region with a composite-field-of-view (CFOV) that matches the sub-region; and
scanning the sub-region along the second direction such that the complete scene is interrogated with the optical signal and sampled by the complete FPA during a scan period.
9. The method according to claim 8 further comprising configuring the receiver such that the CFOV is gap free.
10. The method according to claim 8 further comprising configuring the receiver such that the second angular range of the IFOV is less than the first angular range of the IFOV.
11. The method according to claim 8 further comprising integrating one or more signals generated by the receiver during a scan period.
12. The method according to claim 11 wherein the scanner continuously scans the sub-region along the second direction.
13. The method according to claim 11 wherein the scanner scans the sub-region along the second direction step-wise as a plurality of steps, wherein the lateral extent of each step is matched to the lateral extent of the sub-region.
14. The method according to claim 11 wherein the scanner scans the sub-region along the second direction step-wise as a plurality of steps, wherein the lateral extent of each step is matched to the lateral extent of the IFOV.