hybrid detector, hybrid PMT, HPD, hybrid photomultiplier tube
A hybrid photo detector is a device for detecting very small amounts of light. Due to the low fluctuation, hybrid photodetectors are able to precisely determine the number of photoelectrons initially generated, as long as the maximum recording capacity is not exceeded. These detectors combine the properties of photomultipliers and avalanche photodiodes. Incoming photons are detected by an HPD using a photocathode (e.g. made of gallium arsenide phosphide), which emits a photoelectron with the highest possible quantum yield. This is strongly accelerated within a photomultiplier tube by means of high voltage in a vacuum, so that it finally hits an avalanche diode (electron bombardment). As a result, numerous electrons are released in the APD, so that the original photoelectron is duplicated more than a thousand times. In this way, measurable signals are generated that can be used for data acquisition.
The extremely light-sensitive detectors are used in fluorescence microscopy, fluorescence lifetime microscopy and fluorescence correlation spectroscopy.