Correction Of Time-Resolved Spad Array Measurements For Accurate Single-Photon Time-Resolved Biological Imaging

A 128 x 192 SPAD array (QuantiCam) with an on-chip time-to-digital converter in each pixel is used as a camera in a single-photon time-resolved fluorescence microscope. The SPAD array introduces systematic nonlinearities and timing offset to the measured photon arrival times. This limits the fidelity of the experimental results. A Monte-Carlo algorithm was developed to transform the raw photon time-stamp stream coming from the SPAD array into a corrected virtual "photon" time-stamp stream devoid of the systematic measurement errors. This data is compatible with existing downstream data processing pipelines used in time-correlated single-photon counting. We discuss the calibration measurement, the algorithm, their performance and application to live fluorescence lifetime imaging of photosynthetic organisms.