Shot Noise Analysis for Differential Sampling in Indirect Time of Flight Cameras

Continuous wave Time of Flight cameras obtain depth images by emitting a modulated continuous light wave and measuring the delay of the received signal. One of the main sources of error is shot noise. In this letter we analyze and provide insights about the effect of shot noise when obtaining the phase delay with a new architecture, based on differentiating the phase integrations in the analog domain, and using any number of points in the calculation of the Discrete Fourier Transform (DFT). One of the main findings is that the error depends on the integration time regardless the number of points in the DFT used to calculate the phase offset. Simulated experiments are provided which support the proposed theoretical analysis.