Figure 2.

(a) When photon collection rates are high in TCSPC, the instrument dead times result in loss of information (X) of photons arriving late. This skews the probability density function towards shorter lifetime values and also results in loss of photon efficiency. (b) Typical TCSPC systems therefore operate at low laser powers and low photon count rates (∼1 photon/100 excitation pulses) to avoid photon pileup artefacts. This results in acquisition times of the order of minutes per image. Figure adapted from Wahl et al [13].