High count rate pseudo-random single photon counting system for time-resolved diffuse optical imaging

Abstract

Pseudo-random single photon counting (PRSPC) is a new time-resolved method combining the spread spectrum timeresolved optical measurement method with single photon counting. A continuous wave laser diode is modulated with a pseudo-random bit sequence, while a single photon detector is used to record the pulse sequence in response to the modulated excitation. Periodic cross-correlation is performed to retrieve the impulse response. Compared with conventional time-correlated single photon counting (TCSPC), PRSPC enjoys many advantages such as low cost and high count rate without compromising the sensitivity and time-resolution. In this paper, we report a PRSPC system that can be used for high speed acquisition of the temporal spread function of diffuse photons. It can reach a photon count rate as high as 3Mcps (counts per second). Experimental work has been conducted to demonstrate the system performance. © 2010 Copyright SPIE - The International Society for Optical Engineering.