Photodetector
Photomultiplier (front view)
Electronic components are referred to as photodetectors , also light sensors or optical detectors , optoelectronic sensors , which convert light into an electrical signal using the photoelectric effect or exhibit an electrical resistance that is dependent on the incident radiation . However, the term also refers to applications that have integrated such a radiation-measuring component. In optoelectronics, the term light refers not only to visible light, but also to invisible infrared light and ultraviolet radiation .
An optoelectronic sensor can detect signals (for example a light meter ) or be integrated into an imaging measuring process in which the light-sensitive surface is divided into individual areas ( pixels ) so that an electrical image can be generated in conjunction with a lens and camera electronics . For robotics and medical applications, developments are already under way in the direction of complex visual apparatus using cameras and their signal processing.
Photodetectors that use the external photoelectric effect include:
- Photocells
- Photomultiplier (fast, smallest amounts of light down to single photons )
- Microchannel plate photomultiplier (same principle as the photomultiplier, but with even better time resolution)
Photodetectors that use the internal photoelectric effect include:
- CMOS sensors (e.g. in digital cameras and video cameras )
- CCD sensors (e.g. in digital cameras and video cameras, scanners , spectrometers , fax machines )
- Photodiodes (as a fast sensor for visible light, as well as infrared and ultraviolet; mostly made of silicon , but also of other materials for photo semiconductors )
- pin photodiodes ( e.g. at the end of fiber optic cables and as receivers in remote controls )
- Avalanche photodiodes (for very low light intensities down to individual photons; similar to pin photodiodes, but with internal amplification due to the avalanche effect )
- Position sensitive device (PSD, spatially resolving large-area pin photodiode)
- MSM photodiodes ( metal semiconductor metal photodiodes, basically made up of two Schottky diodes )
- Phototransistors (usually made of silicon, higher signal than photodiodes, but slower than these)
- Photo resistor ( bidirectional , slow, e.g. for light measurement, twilight switch , light meter)
See also
- Radiation detector for other electromagnetic radiation
- Sensors according to the measuring principle # Photoelectronic sensors (optical sensors)