A Range-Gated CMOS SPAD Array for Real-Time 3D Range Imaging

A range image of a scene is produced with a solid-state time of- flight system that uses active illumination and a time-gated single photon avalanche diode (SPAD) array. The distance to a target from the imager is measured by delaying the time gate in small steps and counting the photons of the pixels in each delay step in successive measurements. To achieve a high frame rate, the number of delay steps needed is minimized by limiting the scanning of the depth only to the range of interest. To be able to measure scenes with objects in different ranges, the array has been divided into groups of pixels with independently controlled time gating. This paper demonstrates an algorithm that can be used to control the time gating of the pixel groups in the sensor array to achieve depth maps of the scene with the time-gated SPAD array in real time and at a 70 Hz frame rate.