Measurement of the fluorescence lifetime in scattering media lay frequency-domain photon migration

A method is presented to determine fluorescence decay lifetimes within tiss uelike scattering media. Fluorescence Lifetimes are determined for micromol ar concentrations of the dyes 3,3'-Diethylthiatricarbocyanine Iodide and In docyanine Green by frequency-domain, investigations of light, propagating i n turbid media. Dual-wavelength photon-migration measurements that use inte nsity-modulated sources at excitation and emission wavelengths of the fluor ophores provide optical parameters of the media as well as fluorescence pro perties of the dyes. The deduction of fluorescence lifetimes requires no ca libration with reference fluorophores, and the results are shown to be inde pendent of dye concentration, (C) 1999 Optical Society of America.