We present the use and characterization of a photon-counting detector for increased sensitivity at low signal levels in fluorescence laser scanning microscopy (LSM). Conventional LSM photomultiplier tube detectors utilize analog current integration and thus suffer from excessive noise at low signal levels, introduced during current measurement. In this Letter we describe the implementation of a fast single-photon-counting (SPC) detector on a conventional two-photon laser scanning microscope and detail its use in imaging low fluorescence intensities. We show that for a low photon flux, the SPC detector is shot-noise limited and thus provides increased detection sensitivity compared with analog current integration.
© 2008 Optical Society of America
Original Manuscript: September 8, 2008
Manuscript Accepted: October 14, 2008
Published: December 4, 2008
Vol. 4, Iss. 2 Virtual Journal for Biomedical Optics
Richard K. P. Benninger, William J. Ashby, Elisabeth A. Ring, and David W. Piston, "Single-photon-counting detector for increased sensitivity in two-photon laser scanning microscopy," Opt. Lett. 33, 2895-2897 (2008)