Time-resolved two-photon excited fluorescence spectroscopy based on a streak camera

Combination of fluorescence spectral and temporal resolutions can improve the sensitivity and specificity of biomedical diagnostics. In this paper, we present the development, of a time-resolved two-photon excited fluorescence spectroscopy system that consists of a Ti: Sapphire femtosecond laser, a fluorescence microscope objective, a prism spectrophotometer and a high repetition rate picosecond streak camera. The streak camera and the time-resolved fluorescence spectroscopy system have been calibrated with an F-P etalon and a spectral line lamp respectively. Validation experiment of the system is also performed on two standard fluorescent dyes (Rhodamine 6G and Coumarin 314), and the results agree well with those reported in the literatures. Preliminary experimental results on autofluorescence spectra and lifetimes of freshly picked leaves and in vivo human skin are also presented, which demonstrates the potential applications of this system in tissue discrimination and clinical diagnostics.