Dark Count Statistics in Geiger-Mode Avalanche Photodiode Cameras for 3-D Imaging LADAR
We describe cameras incorporating focal plane arrays of Geiger-mode avalanche photodiodes (GmAPDs) that enable 3-D imaging in laser radar (LADAR) systems operating at wavelengths near 1.0 and 1.5 μm. GmAPDs based on the InGaAsP material system achieve single-photon sensitivity at every pixel of the array and are hybridized to custom CMOS ROICs providing 0.25 ns timing resolution. We present camera-level performance for photon detection efficiency and dark count rate, along with a survey of the evolution of performance for a substantial number of 32 × 32 cameras. We then describe a temporal statistical analysis of the array-level dark count behavior that distinguishes between Poissonian intrinsic dark count rate and non-Poissonian crosstalk counts. We also report the spatial analysis of crosstalk events to complement the statistical temporal analysis. Differences between cameras optimized for the two different wavelengths-1.0 and 1.5 μm-are noted, particularly with regard to crosstalk behavior.