Time-resolved diffuse reflectance at small source-detector separation using a time-gated single-photon avalanche diode

摘要

We demonstrate the feasibility of time-resolved diffuse reflectance at small source-detector separations using a single-photon avalanche diode (SPAD) operated in time-gated mode. Photon time distributions at an interfiber distance of 0.2 cm were obtained on tissue phantoms with a reduced scattering coefficient of 10 cm~(-1), and an absorption coefficient of 0.1 cm~(-1), with a dynamic range of 10~6 and collecting photons at arrival times up to 4 ns. By time-gating the initial photons, carrying information mainly from superficial layers, it is possible to detect longer lived photons that have explored deeper depths even at almost null interfiber distances. The proposed approach should provide higher number of photons at any arrival time, higher contrast, and better spatial resolution as compared to longer interfiber distances.