High frequency scanning response of an APD photocurrent for laser range finder

In this paper, the scanning response of the photocurrent emitted by a large area avalanche photodiode (APD) is studied for a 3D laser camera. This 3D camera is based on a phase-shift laser range-finder to measure distance from 1 to 20 m. To obtain a large field of view of the optical head, a large area APD working as an optoelectronic mixer is used. Photocurrent response versus light spot position above the APD active area is analysed for high frequency measurements. Optoelectronic mixing permits to measure the scanning response phase of the internal photoelectric current. Moreover, it is demonstrated that the signal phase depends on the photoelectric gain. Signal-to-noise ratio and distance measurement error for the 3D camera are then discussed.