Improved High Speed and High Dynamic Range Photon Counting Sensors for Active Imaging

Voxtel proposes a high speed, asynchronous, photon counting receiver for active ranging by unmanned aerial systems (UAS). Sensitivity to single photons is desirable for a low size weight and power (SWAP) UAS-borne active ranging receiver because of the limited laser pulse energy that can be transmitted, and the limited optical aperture available for signal collection. High rate operation is another requirement for a UAS-borne active ranging receiver, because accumulation of multiple pulses on target in a short span of time will be required to deal with atmospheric distortion and to improve the signal-to-noise ratio in photon-starved conditions. Since the distant target in a ranging application will subtend just a few pixels, asynchronous readout of only the pixels that fire will lower the computational burden of range processing by sparsifying the data. The proposed receiver will employ Voxtel"s innovative single carrier multiplication (SCM) avalanche photodiode (APD) technology which can sense single photons in linear mode operation, and a custom readout integrated circuit (ROIC) that will stream detection events from the 88-format detector to a 64-channel time recorder/range processor implemented in a field-programmable gate array (FPGA) board.