Pseudo-random single photon counting system: a high speed implementation and its applications

As a new time-resolved method which combines the spread spectrum time-resolved method with single photon counting, pseudo-random single photon counting (PRSPC) has been proved to have the potential for high speed data acquisition due to high count rate achievable. A continuous wave laser modulated by a pseudo-random bit sequence is used to illuminate the sample, while single photon counting is used to build up the optical signal in response to the excitation. Periodic cross-correlation is performed to retrieve the temporal profile. Besides the high count rate, PRSPC also offers low system cost and portability which are not with the conventional time-correlated single photon counting (TCSPC). In this paper, we report a high speed PRSPC system that can be used for real time acquisition of the temporal spread function (TPSF) of diffuse photons. We also present preliminary experimental work of human blood glucose testing studies by utilizing the PRSPC system.