Development of PIN Diode Detector Arrays for 3D Flash LIDAR Space Applications

Advanced Scientific Concepts, Inc. (ASC) has developed a number of 3D Flash LIDAR systems. Flash LIDAR sensors are 3D video systems that return range and intensity for each pixel in real time. ASC's Flash LIDAR has been used for autonomous berthing with the International Space Station and is currently under development for the OSIRIS-REx asteroid rendezvous mission. Flash LIDAR is also being evaluated by JPL and NASA for Entry Decent and Landing for ALHAT and Mars. All of these applications use avalanche photodiode (APD) arrays in the camera focal plane array. APDs are complex epitaxially grown structures and biased at relatively high voltages (50-70V). These arrays have a poor fill factor that is compensated by micro-lenses. These micro-lenses are restricted to F/#s greater than about 3.3 which in turn limits the effective receive aperture. If micro-lenses were unnecessary, an F/1 receive aperture could increase the collection area by a factor of 10 with no increase in noise. This should result in an increased SNR of approximately 40% but, because of the simplicity of PINs compared to APDs, an increase in reliability as well. PINs are more radiation hard than APDs, are more operationally stable (therefore do not require individual fuses to protect against the development of high dark current pixels), inherently have lower dark current (lower noise), and are inherently more uniform. In addition low-voltage FPA drive electronics is easier to design than high voltage circuitry. These improvements will result in a more reliable higher performance array.