Analysis of Timing Errors in Time-of-Flight LiDAR Using APDs and SPADs Receivers

We analyze the ultimate timing error that can be achieved in the operation of a LiDAR based on the timeof-flight (ToF) measurement of distance using a pulsed light source and two possible detectors in the optic receiver: (i) an avalanche photodiode APD in linear mode, and (ii) a SPAD single photon detector. We analyze both the random and systematic contributions to the total error and find that the latter becomes dominant at large (>102) number of detected photons Nph. However, the systematic error can be cancelled by a separate measurement of Nph. As a conclusion, it is found that, aside from a multiplicative factor of the order of unity, all the schemes supply a timing error given by tau /root Nph, where tau is the characteristic time describing the illumination waveform. The theory we have developed provides a theoretical framework for the evaluation of the precision of time-of-flight measurement, and the results are applicable as a benchmark of the timing performance obtained by practical instruments.

Automated summary

In this study, the ultimate timing error in LiDAR operation using time-of-flight measurement is analyzed, with systematic error becoming dominant at large number of detected photons. However, this systematic error can be canceled out by a separate measurement of the number of photons.