Laser-based distance measurement using picosecond resolution time-correlated single-photon counting

In this paper, we report results obtained with a time-of-flight ranging/scanning system based on time-correlated single-photon counting. This system uses a pulsed picosecond diode laser and detects the scattered signal from a non-cooperative target surface using a semiconductor single-photon detector. A demonstration system has been constructed and used to examine the depth resolution obtainable as a function of the integrated number of photon returns. The depth resolution has been examined for integrated photon returns varying by five orders of magnitude, both by obtaining experimental measurements and by computer simulation. Depth resolutions of approximately 3 mm were obtained for only ten returned photons. The effect of the background signal, originating either from temporally uncorrelated light signals or from detector noise, has also been examined.