Fluorescence lifetime imaging with pulsed diode laser enabled stimulated emission

We present here a stimulated emission based fluorescence lifetime imaging (FLIM) scheme using a pair of synchronized diode lasers operating at gain switched pulse mode. The two semiconductor lasers, with wavelengths at 635 nm and 700 nm, serve as the excitation and the stimulation light sources for the ATTO647N labeled sample, respectively. FLIM is readily achieved with their relative time delay controlled electronically. The coherent nature of the stimulated emission signal also allows FLIM at long working distance. In this way, a high performance all-semiconductor FLIM module is realized in a flexible, compact, and cost effective configuration.