Fluorescence lifetime estimation by 1-bit photon autocorrelation procedure from time-series data recorded using a high-speed digitizer

Abstract

We propose a photon-counting fluorescence lifetime measurement scheme that uses a 1-bit autocorrelation procedure. The proposed scheme is an extension of the previously reported lifetime measurements using the autocorrelation analysis (Nishimura et al. in: Phys Med Biol 48:N283–N290, 2003; Nishimura et al. in: J Biomed Opt 12:020503, 2007). The fluorescence photons obtained from a high-repetition-rate, pulsed excitation light source are fed into a photodetector, and its output photoelectron pulse train is stored in a transient memory composed of a high-speed digitizer that retains time information over a large number of excitation cycles. After the stored data have been binarized, a 1-bit autocorrelation procedure is performed to estimate the fluorescence lifetimes through a repetitive curve-fitting process. We could successfully demonstrate this scheme in nanosecond fluorescence lifetime measurements with a progressed high-speed digitizer, which requires no synchronization with the excitation timing. To date, the minimum sampling interval and the maximum number of sample points of the digitizer are 400 ps and ~ 1 × 109, respectively. We present the results of some fluorescence lifetime measurements of standard samples that were performed as a proof of principle experiment.