Empirical Verification of Range Resolution for a TOF Range Image Sensor with Periodical Charge Draining Operation under Influence of Ambient Light

Abstract

The range resolution of a time-of-flight (TOF) range image sensor with periodical charge-draining operation is analyzed under the influence of ambient light. The analysis explains the effectiveness of a small duty light pulse and a periodical charge-draining structure to reduce the influence of ambient light. A theoretical model of range resolution taking into consideration factors of the duty ratio, the ambient light component, and the diffusion component is presented. The theoretical model under the influence of ambient light well agrees with the experimental results. The offset-charge-canceling technique using two sub-frames effectively enables accurate range measurements under ambient light.