Photoelectric sensor

    Photoelectric sensor is generally composed of processing path and processing element. Its basic principle is to convert the measured change into the change of the optical signal based on the photoelectric effect, and then further convert the non electric signal into the electric signal with the help of the photoelectric element. Photoelectric effect refers to irradiating an object with light, which can be regarded as a series of photons with a certain energy bombarding on the object. At this time, the photon energy is transferred to the electron, and all the energy of a photon is absorbed by an electron at one time. After the electron obtains the energy transferred by the photons, its state will change, So that the object irradiated by light has corresponding electric effect.

Generally, photoelectric effects are divided into three categories：
    (1) The phenomenon that electrons can escape from the surface of objects under the action of light is called external photoelectric effect, such as phototube, photomultiplier tube, etc;
    (2) The phenomenon that can change the resistivity of objects under the action of light is called internal photoelectric effect, such as photoresistor, phototransistor, etc;
    (3) Under the action of light, the phenomenon that the object produces certain direction electromotive force is called photovoltaic effect, such as photocell.

    Photoelectric detection method has the advantages of high precision, fast response, non-contact and so on, and can measure many parameters, the structure of the sensor is simple, the form is flexible, so the photoelectric sensor is widely used in detection and control.

    Photoelectric sensor is the key component to realize photoelectric conversion in various photoelectric detection systems. It is a device that converts optical signal (visible and ultraviolet laser light) into electrical signal.

 

    Photoelectric sensor is a kind of sensor which uses photoelectric devices as conversion elements. It can be used to detect the non electric physical quantities that directly cause the change of light quantity, such as light intensity, illumination, radiation temperature measurement, gas composition analysis, etc; It can also be used to detect other non electric quantities that can be converted into light quantity, such as the diameter of parts, surface roughness, strain, displacement, vibration, velocity, acceleration, as well as the identification of the shape and working state of objects. Photoelectric sensor has the characteristics of non-contact, fast response and reliable performance, so it is widely used in industrial automation devices and robots. The emergence of new photoelectric devices, especially the birth of CCD image sensor, opens a new page for the further application of photoelectric sensor.