Development of photoelectric sensors

1839a.e. Bekkerel found that when light falls on two metal electrodes immersed in dielectric liquid, a potential will be generated between them, which is later called photovoltaic effect. In 1873, w Smith and Ch Mayer discovered the photoconductive effect of selenium. 1887 Hz found the external photoelectric effect. Photoelectric tube and photomultiplier tube based on external photoelectric effect are vacuum tube or ion tube devices, which were widely used in 1950s and 1960s and continue to be used in some occasions. Although T.W. Case obtained the patent right of thallium sulfide photoconductive detector as early as 19 19, semiconductor photosensitive elements began to develop rapidly with the development of semiconductor technology after the 1960s. During this period, various photoelectric materials have been comprehensively studied and widely used. Their structures are single crystal and polycrystalline films, as well as amorphous, and their components are elemental semiconductors and compound semiconductors, as well as mixed crystals. The two most important ones are silicon and mercury cadmium telluride. Silicon is rich in raw materials and mature in technology, which is an excellent material for manufacturing photoelectric devices from near infrared to ultraviolet band. Mercury cadmium telluride is a mixed crystal of mercury telluride and cadmium telluride, and it is an excellent infrared photosensitive material. Through the study of photoelectric effect and device principle, a variety of photoelectric devices (such as photoresistor, photodiode, phototransistor, field effect photovoltaic cell, avalanche photodiode, charge coupled device, etc. ) has been developed and is suitable for different occasions. With the development of thin film technology, planar technology and large-scale integrated circuit technology, the manufacturing technology of photoelectric sensors has reached a high level, and the cost of products has also been greatly reduced. The focal plane integrated photosensitive array, known as the new generation camera device, is replacing the traditional scanning camera system. The latest development direction of photoelectric transducer is to adopt new technologies such as organic chemical vapor deposition, molecular beam epitaxy, monolayer growth and heterojunction. The application fields of photoelectric sensors have been extended to textile, papermaking, printing, medical treatment, environmental protection and other fields. New progress has also been made in the research of traditional application fields such as infrared detection, radiation measurement, optical fiber communication and automatic control. For example, the self-calibration technology of silicon photodiode provides a promising new method for absolute measurement of optical radiation.