We introduce a new algorithm for computing correlations of photon arrival time data acquired in single-molecule fluorescence spectroscopy and fluorescence correlation spectroscopy (FCS). The algorithm is based on rewriting the correlation as a counting operation on photon pairs and can be used with arbitrary bin widths and spacing. The flexibility of the algorithm is demonstrated by use of FCS simulations and single-molecule photon antibunching experiments. Execution speed is comparable to the commonly used multiple-tau correlation technique. Wide bin spacings are possible that allow for real-time software calculation of correlations, even for high count rates.
© 2006 Optical Society of America
Original Manuscript: October 24, 2005
Manuscript Accepted: November 11, 2005
Vol. 1, Iss. 4 Virtual Journal for Biomedical Optics
Ted A. Laurence, Samantha Fore, and Thomas Huser, "Fast, flexible algorithm for calculating photon correlations," Opt. Lett. 31, 829-831 (2006)