The transmitter aims at the target to emit light beams, which generally come from semiconductor light sources, light emitting diodes, laser diodes and infrared emitting diodes. Continuously emit light beams or change the pulse width. The receiver consists of photodiode, phototransistor and photocell. In front of the receiver, optical elements such as lens and aperture are installed. Behind it is a detection circuit, which can filter out effective signals and apply them. In addition, there are emission plates and optical fibers in the structural elements of photoelectric switch. The triangular reflector is a solid emitter. It includes