Photomultiplier tube

Definition: Photomultiplier tube (PMT) is a photodetection device equipped with a photocathode and electron multiplier utilized for its high gain and low light sensing capabilities. When a photon strikes the photocathode, a single photoelectron is emitted from this site. The photoelectron is then accelerated using electric fields to a structure known as a dynode. After striking the dynode, additional electrons are released which are then sent to another dynode. This process will continue for as many dynodes as contained in the PMT. The resulting photoelectron gain is ~1×106 to 1×107. In analog mode, the output of the device is a current that can be measured directly from the device. Additionally, a PMT can operate in photon counting mode, which, when combined with a pulse height discriminator and timing and counting electronics, may be utilized for TD-fNIRS.

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References: https://doi.org/10.1016/B0-12-369397-7/00529-X,

https://hamamatsu.magnet.fsu.edu/articles/photomultipliers.html

Related terms: Avalanche Photodiode, Silicon Photomultiplier, Detector, Sensor