Photomultiplier, has the function of amplification, photomultiplier tube established on the basis of the theory of the outer photoelectric effect, secondary electron emission and electron optics, combined with high gain, low noise, high frequency response and large signal receiving area and other characteristics, is a very high sensitivity and ultra-fast time response of the light-sensitive electro-vacuum devices can work in the ultraviolet, visible and near infrared region of the spectral region. Day-blind ultraviolet photomultiplier tubes are insensitive to visible, near-ultraviolet and other spectral radiation outside the day-blind ultraviolet region, and are characterized by low noise (dark current less than 1nA), fast response, and large receiving area.
Photoelectric functional crystals mainly use photoelectric conversion of functional crystals, there are many types, photocoupler is one of them;
Photoelectric converter is a kind of similar to the baseband MODEM (digital modem) equipment, and the baseband MODEM is different from access to the fiber optic leased line, is the optical signal. Currently mainly used in the field of communications.