For Time-Correlated Single Photon Counting (TCSPC) measurements, a precise synchronization signal from the pulsed excitation system is crucial. PicoQuant excitation sources, such as the PDL 800-D driven laser or LED heads provide an electrical sync signal suitable for e.g. the TCSPC boards / modules HydraHarp 400, PicoHarp 300 or TimeHarp 200.

For laser systems without an appropriate electrical sync signal, the TDA 200 photodiode is used to synchronize the timing electronics. It is built around a silicon pin photodiode with an active area of 0.5 mm diameter and can be used from 350 to 1100 nm with peak sensitivity at around 800 nm. When a small fraction of the excitation beam is directed towards the TDA 200 unit, it responds to each excitation pulse with a fast (typ. 500 ps) negative output pulse, that can be directly coupled to the TCSPC device. Due to the principle of TCSPC, the timing accuracy is well below the detector pulse width / rise time, typically just a few tens of picoseconds. The multicolor LED indicator facilitates the adjustment of the light intensity to meet the requirements of the sync input of the TCSPC device. The green light turns on softly when the peak amplitude of the output pulse reaches -100 mV and turns to red if it exceeds -350 mV. If necessary, place a suitable filter into the holder in front of the sensor's entry port. Overexposure of the pin diode does not damage the TDA 200, but it may produce output pulses with more than -1 V peak amplitude, which is more than recommended for the TCSPC units. The required 12V DC power supply is shipped with the product.