A hardware approach to overcome pile-up in TCSPC: from principles to field verification

With the development of advanced and dedicated timing instrumentation, Time-Correlated Single-Photon Counting (TCSPC) has become the de-facto standard for the measurement of low-light signals in a wide variety of applications, from fluorescence observation in biology to 3D scanning in laser ranging. Despite the huge technical improvements, the historical pile-up limitation still represents an open issue, that reduces the maximum acquisition rate to few percent (1-5 %) of the laser excitation rate. This prevents high-speed and real-time exploitation of TCSPC, thus reducing the range of applications that can benefit from such a powerful technique. To overcome this limitation, in 2017 we proposed a novel theoretical approach based on a time-matching between detector dead time and laser period, and in 2021 we designed the first system implementing this new technique. Preliminary results showed a good accordance between the theoretical framework and practical experiments with standard fluorescence dies up to a rate of 32 Mcps. Since then, we have been working on the exploitation of our system in further practical measurements, to perform a deeper validation of its potential. In particular, we have explored the application of our system into a lidar experiment, as no a-priori knowledge is necessary on the specific type of signal. In this proceeding, we present an overview of our work from the theoretical principles to the field verification.