Fig. 4

Fluorescence lifetime fitting of coumarin 6 in ethanol. A saturated solution of coumarin 6 in ethanol was loaded into an FEP sample tube and imaged on the light-sheet SPAD system with 0.4 mW excitation laser power and 3 s integration time using a green emission filter (550/100  nm). (a) The blue curve shows the aggregated decay histogram from all array pixels before correcting for the inter-pixel delays. The red curve shows the aggregated decay histogram after such correction. The corrected decay histogram has a faster rise and higher peak, whereas the uncorrected decay histogram has a slower rise and is temporally broadened. (b) The aggregated decay histogram of all pixels after timing skew correction was fit to a single-exponential decay model using an iterative reconvolution algorithm that performs a least-squares minimization of the residuals. A fluorescence lifetime of 2.51 ns is estimated which agrees with reported published values.^62–64