Uncooled, Long-Life Wavefront/Tracking Sensor

A highly reliable InAlAs/InGaAs avalanche photodiode (APD) focal plane array (FPA) will be developed to replace the electron-bombarded charge-coupled device (EBCCD) camera presently used for Airborne Laser (ABL) wavefront sensing applications. Based on technology with a nominal lifetime of 105 hours of continuous operation, Voxtel’s monolithic solid-state architecture is both more manufacturable and rugged than the existing tube-based instrument. Two innovations lie at the heart of the new wavefront sensor: 1) novel low-noise APD designs and 2) a proprietary readout integrated circuit (ROIC) with extremely low input noise. Development of new APD designs was begun during Phase I, supported by substantial device testing and simulation efforts. A working version of the ROIC already exists and has demonstrated performance characteristics compatible with the wavefront-sensing mission. Building upon this cornerstone, two APD detector designs – one well established and the other more sophisticated – will be manufactured during Phase II. Fabricated as 8×8 FPAs, the low-noise near infrared (NIR) APDs will be characterized and integrated with high bandwidth ROICs in a prototype camera system. The technology readiness of Voxtel’s approach will be demonstrated through performance demonstrations and reliability growth testing.