What is the principle of a photoelectric sensor?

Photoelectric sensors in general, there are three components, they are divided into: transmitter, receiver and detection circuit.

The transmitter emits a beam of light aimed at the target, which is generally derived from semiconductor light sources, light-emitting diodes (LEDs), laser diodes and infrared emitting diodes. The beam is emitted uninterruptedly or the pulse width is varied. The receiver has a photodiode, phototransistor, photocell composition. In front of the receiver, there are optical elements such as lenses and apertures. Behind it is the detection circuit, which filters out the effective signal and applies that signal.


In addition, among the structural elements of the photoelectric switch are the emitter plate and the optical fibre.

The triangular reflector plate is the emitting device with a solid structure. It consists of a very small triangular cone of reflective material that enables the beam to return accurately from the reflector plate in a practical sense. It is possible to vary the emission angle in the range of 0 to 25 from the optical axis, so that the beam is almost from one line of emission, and after reflection, still returns from this line of reflection.