Time-correlated photon counting system

摘要

The photon counting system with a high registration rate uses the time difference between an individual photon pulse and a synchronisation pulse, provided by a laser, to deliver a proportional output signal, via a time/amplitude converter. An auxiliary signal is added to the output signal before supplying it to an A/D converter (ADC) providing an output word, subtracted from the output word of the auxiliary signal, to provide an address for the time point of the input pulse. Pref. the auxiliary signal is provided by a D/A converter (DAC) controlled by a counter (CNT) to obtain a sawtooth output voltage, increased by one step for each counter clock.