Under normal circumstances, a photoelectric sensor consists of two parts: a processing path and a processing element. Its basic principle is to use the photoelectric effect to convert the measured change into a change in light signal, and then use photoelectric elements to further convert the non-electrical signal into an electrical signal.
The photoelectric effect refers to the phenomenon where light shines on an object, which can be viewed as photons of a certain energy level bombarding the object. The energy of the photons is transferred to electrons, and all the energy of an electron is absorbed by that electron at once. When the electron receives the energy transferred by the photons, its state changes, thus producing a corresponding electrical effect on the object. The photoelectric effect is generally divided into three categories:
(1) The phenomenon that electrons can escape from the surface of an object under the action of light is called the external photoelectric effect, such as phototubes and photomultiplier tubes;
(2) The phenomenon that causes a change in the resistivity of an object under the influence of light is called the internal photoelectric effect, such as photoresistors and phototransistors;
(3) The phenomenon that an object generates an electromotive force in a certain direction under the action of light is called photovoltaic effect, such as photovoltaic cells.
Photoelectric sensors are devices that convert optical signals (visible and ultraviolet laser light) into electronic signals. They are key components for achieving photoelectric conversion in various photoelectric detection systems.
A photoelectric sensor is a sensor that uses optoelectronic devices as conversion elements. This system can detect non-electrical physical quantities that directly cause changes in light intensity, such as light intensity, illuminance, radiation temperature, and gas composition analysis; it can also detect other non-electrical factors, such as part diameter, surface roughness, strain, displacement, vibration, velocity, acceleration, object shape, and working condition recognition, thus converting them into changes in light intensity. Photoelectric sensors are characterized by non-contact operation, fast response speed, and reliable performance, and are therefore widely used in industrial automation equipment and robots. New types of optoelectronic devices are constantly emerging, especially the advent of CCD image sensors, which has opened up new possibilities for the further application of photoelectric sensors.
