Aull et al. “Three-Dimensional Imaging Laser Radars with Geiger-Mode Avalanche Photodiode Arrays

radars (ladars) that feature few-centimeter range resolution, thousands of pixels, and capture of an entire 3D image on a single laser pulse. The transmitters are based on diode-pumped solid-state microchip lasers that are passively Q-switched. The receivers are based on microelectronic arrays of avalanche photodiodes (APDs) operating in Geiger (photon counting) mode, with integrated timing circuitry for each pixel. Ladars using these laser and detector technologies offer not only high performance, but also compact packaging, ruggedness, and high efficiency. Potential applications include advanced interceptor seekers, combat identification, navigation of autonomous robots and vehicles, surveillance, and topography. Early experiments with a single detector showed the feasibility of using a Geiger-mode APD for 3D imaging. Subsequently, we constructed a first-generation (“brassboard”) 3D ladar incorporating a 4 × 4 array of Geiger-mode APDs and a microchip laser. Experiments with the brassboard and a low-light-level camera showed that in some important situations targets can be better detected and identified fro