A photoelectric sensor generally consists of two parts: a processing path and a processing element

A photoelectric sensor generally consists of two parts: a processing path and a processing element. The basic principle is based on the photoelectric effect, which converts the measured changes into changes in optical signals, and then further converts non electrical signals into electrical signals with the help of photoelectric components. The photoelectric effect refers to the use of light to irradiate an object, which can be seen as a series of photons with a certain energy hitting the object. At this time, the energy of the photons is transmitted to the electrons, and all the energy of a photon is absorbed by an electron at once. After the electrons receive the energy transmitted by the photons, their state will change, causing the object irradiated by light to produce corresponding electrical effects. The photoelectric effect is usually divided into three categories: (1) the phenomenon that electrons can overflow from the surface of an object under the action of light is called the external photoelectric effect, such as phototubes, photomultiplier tubes, etc; (2) The phenomenon of changing the resistivity of an object under the action of light is called the internal photoelectric effect, such as photoresistors, phototransistors, etc; (3) The phenomenon of an object generating a certain directional electromotive force under the action of light is called the photovoltaic effect, such as in photovoltaic cells. [2]