25th World's leading trade fair and congress for components, systems and applications of photonics
April 26–29, 2022 | Messe München
25th World's leading trade fair and congress for components, systems and applications of photonics
April 26–29, 2022 | Messe München
Photomultipliers – light converters with a great effect
Like photovoltaic cells, photomultipliers are based on the photoelectric effect – they convert photons into electrons. But rather than being optimized for output and efficiency, they are optimized for sensitivity and minimal noise in order to detect even the smallest quantities of light in measurement devices.
In addition to photomultipliers (PMTs), avalanche photodiodes (APDs) and photon counting detectors are also used. When light hits the semiconductor diodes, it is converted into electrical energy.
Because in many applications this involves analyzing very weak light signals – such as light or fluorescence scattered by cells – the photoelectric detectors have integrated signal boosters. As the name avalanche suggests, photons in APDs release a real flood of charge: One photon can create hundreds or even thousands of electrons. This boosting effect makes it possible to detect tiny quantities of light, for example in medical analysis devices.
PMTs and APDs cover the most diverse range of the spectrum, from ultraviolet to infrared.