Ladar System with Adaptive Receiver

Abstract

Disclosed herein are various embodiments for a ladar system that includes an adaptive ladar receiver whereby the active pixels in a photodetector array used for reception of ladar pulse returns can be adaptively controlled based at least in part on where the ladar pulses were targeted by the ladar transmitter.

What is claimed is: 
     
         1 . A ladar system comprising:
 a first mirror for scanning across a field of view in a resonant mode;   a second mirror for scanning across the field of view in a point-to-point mode that varies as a function of a shot list, the shot list comprising a plurality of locations for range points in a scan area of the field of view that are to be targeted with ladar pulse shots;   a laser source that transmits ladar pulse shots toward the targeted range points via the first and second mirrors in accordance with the shot list;   a photodetector array comprising a plurality of photodetector pixels that sense incident light representative of returns from the transmitted ladar pules shots; and   a circuit that adaptively controls which of the photodetector pixels are used for reading out signals corresponding to the sensed incident light signals over time based on a mapping relationship between the photodetector pixels and the locations for the targeted range points; and   wherein the circuit includes feedback circuitry that amplifies outputs from the photodetector pixels in a controlled feedback loop.   
     
     
         2 . The system of  claim 1  wherein the circuit selects defined subsets of the photodetector pixels to use for reading out the signals corresponding to the sensed incident light signals over time based on the mapping relationship. 
     
     
         3 . The system of  claim 2  wherein the circuit selects the defined subsets in a pattern that follows the shot list in accordance with the mapping relationship. 
     
     
         4 . The system of  claim 3  wherein the circuit includes a multiplexer that controls which of the photodetector pixels are included in the defined subsets based on a control signal, wherein the control signal varies based on the shot list. 
     
     
         5 . The system of  claim 4  wherein the feedback circuitry includes amplifiers that are operatively between the photodetector array and the multiplexer. 
     
     
         6 . The system of  claim 5  wherein the photodetector array is resident on a substrate, and wherein the amplifiers are embedded in the substrate. 
     
     
         7 . The system of  claim 4  wherein the feedback circuitry serves as a matching network in resonance with the returns. 
     
     
         8 . The system of  claim 7  wherein the matching network is present on all input lines to the multiplexer. 
     
     
         9 . The system of  claim 3  wherein the circuit further includes a control circuit that generates the control signal based on the shot list. 
     
     
         10 . The system of  claim 3  further comprising:
 a signal processing circuit that detects the returns based on the read out signals selected by the multiplexer. 
 
     
     
         11 . The system of  claim 2  wherein the circuit selectively controls which of the photodetector pixels are eligible for inclusion in the defined subsets based on feedback with respect to prior frames. 
     
     
         12 . The system of  claim 11  wherein the circuit generates an adaptive fault tolerance mask that adjusts which of the photodetector pixels are eligible for inclusion in the defined subsets based on feedback from prior frames that indicates whether any of the photodetector pixels are malfunctioning. 
     
     
         13 . The system of  claim 11  wherein the circuit generates an adaptive mask that controls a dynamic range for the read out signals by adjusting how many of the photodetector pixels are to be included in the defined subsets based on feedback from prior frames. 
     
     
         14 . The system of  claim 11  wherein the circuit generates an adaptive mask that adjusts which of the photodetector pixels are eligible for inclusion in the defined subsets based on feedback from prior frames that indicates a presence of interfering light that would impact one or more of the photodetector pixels. 
     
     
         15 . The system of  claim 11  wherein the circuit generates an adaptive mask that adjusts which of the photodetector pixels are eligible for inclusion in the defined subsets based on feedback from prior frames that indicates a presence of a scattering object that would impact one or more of the photodetector pixels. 
     
     
         16 . The system of  claim 11  wherein the circuit generates an adaptive mask that removes a center photodetector pixel from the defined subsets to reduce saturation risk based on feedback from prior frames. 
     
     
         17 . The system of  claim 2  wherein the circuit adjusts timing for the transmitted ladar pulse shots based on feedback from prior frames to reduce interference on the photodetector pixels of the defined subsets. 
     
     
         18 . The system of  claim 11  wherein the feedback from prior frames comprises data derived from prior ladar pulse returns. 
     
     
         19 . The system of  claim 11  wherein the prior frames comprise video frames. 
     
     
         20 . The system of  claim 2  wherein the defined subsets change over time with respect to how many of the photodetector pixels are included in the defined subsets. 
     
     
         21 . The system of  claim 1  wherein the feedback circuitry serves as a matching network in resonance with the returns. 
     
     
         22 . The system of  claim 1  wherein the feedback circuitry is reset at each ladar pulse shot. 
     
     
         23 . The system of  claim 1  wherein the circuit adjusts shot energy for one or more of the ladar pulse shots on the shot list based on feedback from prior frames. 
     
     
         24 . The system of  claim 1  wherein the circuit adds or removes ladar pulse shots to or from the shot list based on feedback from prior frames. 
     
     
         25 . The system of  claim 1  further comprising:
 a processor that executes a range point down selection algorithm based on environmental scene data to select a subset of range points in the field of view to be targeted with the ladar pulse shots. 
 
     
     
         26 . The system of  claim 1  wherein the transmitted ladar pulse shots exhibit a Gaussian pulse shape. 
     
     
         27 . The system of  claim 1  wherein the first and second mirrors scan along axes that are orthogonal relative to each other. 
     
     
         28 . A ladar method comprising:
 scanning a first mirror across a field of view in a resonant mode;   scanning a second mirror across the field of view in a point-to-point mode that varies as a function of a shot list, the shot list comprising a plurality of locations for range points in a scan area of the field of view that are to be targeted with ladar pulse shots;   transmitting ladar pulse shots toward the targeted range points via the first and second mirrors in accordance with the shot list;   receiving incident light by a photodetector array, the photodetector array comprising a plurality of photodetector pixels that sense the received incident light, wherein the received incident light is representative of returns from the transmitted ladar pules shots;   adaptively controlling which of the photodetector pixels are used for reading out signals corresponding to the sensed incident light signals over time based on a mapping relationship between the photodetector pixels and the locations for the targeted range points; and   amplifying outputs from the photodetector pixels in a controlled feedback loop.   
     
     
         29 . The method of  claim 28  wherein the adaptively controlling step comprises selecting defined subsets of the photodetector pixels to use for reading out the signals corresponding to the sensed incident light signals over time based on the mapping relationship. 
     
     
         30 . The method of  claim 29  wherein the selecting step comprises selecting the defined subsets in a pattern that follows the shot list in accordance with the mapping relationship.