Real-time time-domain fluorescence lifetime imaging including single-shot acquisition with a segmented optical image intensifier

High-speed (video-rate) fluorescence lifetime imaging (FLIM) is reported using two different time-domain approaches based on gated optical image intensifier technology. The first approach utilizes a rapidly switchable variable delay generator with sequential image acquisition, while the second employs a novel segmented gated optical imager to acquire lifetime maps in a single shot. Lifetimes are fitted using both a non-linear least-squares fit analysis and the rapid lifetime determination method. Monte Carlo simulations were used to optimize the acquisition parameters and a comparison between theory and experiment is presented. The importance of single-shot imaging to minimize the deleterious impact of sample movements is highlighted. Real-time FLIM movies of multi-well plate samples and tissue autofluorescence are presented.