A novel three observation-windows measurement scheme for SPAD fluorescence lifetime imaging detector

This paper presents a novel three observation-windows scheme for fluorescence lifetime imaging (FLIM). The repeated integration is operated in three overlapped or discrete observation windows with nanosecond-range duration to obtain photon counting data, which can effectively reduce relative standard deviation in fluorescence lifetime evaluation. Further, based on this three observation-windows detection method, a single photon avalanche diodes (SPAD) pixel circuit including two analog counters is proposed to acquire two precise photon counting data in one fluorescence decay period. Accordingly, imaging speed and imaging quality can be improved.