What Is Time Correlated Single Photon Counting (TCSPC)Time-
Correlated Single Photon Counting (TCSPC) is a technique to
record low level light signals with picosecond time resolution.
Typical applications are TCSPC works best for Time-Correlated
Single Photon Counting is based on the detection of single
photons of a periodical light signal, the measurement of the
detection times of the individual photons and the reconstruction
of the waveform from the individual time measurements. The
method makes use of the fact that for low level, high repetition
rate signals the light intensity is usually so low that the
probability of detecting one photon in one signal period is much
less than one. Therefore, the detection of several photons can
be neglected and the principle shown in the figure below can be
used: The detector signal consists of a train of randomly
distributed pulses due to the detection of the individual
photons. There are many signal periods without photons, other
signal periods contain one photon pulse.