Hyper Temporal Lidar with Multi-Channel Readout of Returns
A lidar receiver can employ multiple readout channels that are capable of simultaneously reading out sensed signals from different pixel sets of a photodetector array in order to detect different returns from different laser pulse shots. In doing so, the lidar receiver can support the use of overlapping detection intervals when collecting signal data for detecting the different returns from the different laser pulse shots.
1 . A lidar system comprising:
a photodetector array, the photodetector array comprising a plurality of pixels for sensing signals representative of incident light on the pixels;
a plurality of readout channels from the photodetector array, wherein the readout channels permit a plurality of readouts of sensed signals from different sets of the pixels at the same time;
a signal processing circuit; and
a control circuit;
wherein the control circuit determines a plurality of detection intervals for controlling the signal processing circuit to detect returns from a plurality of laser pulse shots via different sets of the pixels; and
wherein the signal processing circuit processes a plurality of sensed signals read out from the photodetector array to (1) detect the returns and (2) compute return information based on the detected returns; and
2 . The system of claim 1 wherein the readout channels allow for control circuit to define a plurality of detection intervals that overlap.
3 . The system of claim 1 wherein a plurality of the detection intervals are overlapping.
4 . The system of claim 1 wherein the control circuit identifies the different pixel sets to read out from based on a plurality of range points that are targeted by the laser pulse shots.
5 . The system of claim 4 wherein the shot list identifies the targeted range points for the laser pulse shots by azimuth and elevation angles.
6 . The system of claim 1 wherein each of the different pixel sets comprises one or more of the pixels of the array.
7 . The system of claim 1 wherein each determined detection interval has a corresponding pixel set from which sensed signals are read out, and wherein each of a plurality of the determined detection intervals comprises (1) first data that indicates when to start collection from its corresponding pixel set and (2) second data that indicates when to stop collection its corresponding pixel set.
8 . The system of claim 7 wherein, for each of a plurality of the determined detection intervals, the first and second data comprise estimates of minimum and maximum ranges for the range point targeted by a laser pulse shot associated with that determined detection interval.
9 . The system of claim 8 wherein the control circuit translates the minimum and maximum range estimates into start and stop collection times for the pixel sets corresponding to the determined detection intervals.
10 . The system of claim 1 wherein the control circuit activates pixels of the array to be used for detecting the returns sufficiently prior to when collections are to start from the activated pixels for a pixel settle time to have passed when the collections are to start from the activated pixels.
11 . The system of claim 10 wherein the signal processing circuit comprises a plurality of processors that share processing of the sensed signals.
12 . The system of claim 10 wherein the signal processing circuit updates a lidar point cloud with the computed return information.
13 . The system claim 1 further comprising:
a lidar transmitter, wherein the lidar transmitter comprises a scannable mirror, and wherein the lidar transmitter transmits the laser pulse shots toward targeted range points via the scannable mirror.
14 . The system of claim 13 wherein the lidar transmitter scans the scannable mirror in a resonant mode.
15 . The system of claim 14 wherein the lidar transmitter scans the scannable mirror in the resonant mode at a scan frequency in a range between 100 Hz and 20 kHz.
16 . The system of claim 14 wherein the lidar transmitter scans the scannable mirror in the resonant mode at a scan frequency in a range between 10 kHz and 15 kHz.
17 . The system of claim 13 wherein the scannable mirror comprises a first scannable mirror and a second scannable mirror, wherein the lidar transmitter transmits the laser pulse shots toward the targeted range points via the first and second scannable mirrors.
18 . The system of claim 17 wherein the lidar transmitter scans the second scannable mirror in a point-to-point mode according to a step function that varies as a function of the range points targeted with the laser pulse shots.
19 . The system of claim 17 wherein the second scannable mirror is optically downstream from the first scannable mirror.
20 . The system of claim 13 wherein the lidar transmitter and the photodetector circuit are in a bistatic arrangement with respect to each other.
21 . The system of claim 13 further comprising a laser source that generates the laser pulse shots, and wherein the control circuit schedules the laser pulse shots in the shot list according to a laser energy model for the laser source.
22 . The system of claim 21 wherein the control circuit schedules the laser pulse shots in the shot list according to the laser energy model and a mirror motion model for the scannable mirror.
23 . The system of claim 1 wherein the array comprises a two-dimensional (2D) array of pixels.
24 . A method comprising:
sensing incident light corresponding to a plurality of returns from a plurality of laser pulse shots, wherein the sensing step is performed by a photodetector array comprising a plurality of pixels; and
simultaneously reading sensed signals from a plurality of different sets of pixels of the photodetector array via a plurality of readout channels; and
detecting different returns from the laser pulse shots based on different sensed signals read out by different readout channels.
25 . The method of claim 24 further comprising:
determining a plurality of detection intervals that govern when the reading step is performed by a readout channel to obtain signal data corresponding to different returns from different laser pulse shots.
26 . The method of claim 25 wherein the determining step comprises determining the detection intervals based on defined criteria, wherein the defined criteria includes estimates of ranges for objects to be detected by the laser pulse shots.
27 . The method of claim 25 wherein the determined detection intervals include overlapping detection intervals.