29 Oct 2019 LASER COMPONENTS has been supplying APDs for over fifteen years and these industrial grade detectors are the heart of our photon counting devices. The COUNT series is a range of single photon counting units with the performance optimised in the wavelength range 500 to 900nm. The COUNT-T has an unrivalled quantum efficiency, typically 75% in the red region of the spectrum with a timing resolution of 350ps, providing a level of performance that often outperforms photomultiplier tubes.
These modules feature a simple robust design combining the low noise APD with specially developed quenching and signal processing electronics. Incoming photons produce corresponding electrical pulses which are read out as a TTL signal. The device can also be supplied with an optional fibre connector providing a convenient method for sampling from a multimode optical fibre.
Fluorescence lifetime measurements based on near field microscopy have found applications in various fields such as analytical chemistry, medicine and biology. The fluorescent molecule is cycled between its ground and excited state by a sequence of laser pulses. The excited state exists for a finite time, the fluorescence lifetime which is unique to a particular molecule and allows its identification. This approach results in very low levels of light reaching the sensor requiring that the detector has a high level photon conversion efficiency and responsivity. Photomultipliers have been widely used in this application but have low photon detection efficiency which means about two thirds of the incident light does not contribute to the signal. The COUNT module with its much higher level of photon conversion efficiency ensures that this additional signal is not wasted.
More Information https://www.lasercomponents.com/uk/photon-counter/single-photon-counting-modules/ | 
