Rectangular photoelectric sensors use light to detect the distance, absence, or presence of objects in factory automation operations. Also known as electric eyes, they tell machinery what’s happening in automated processes to keep them running efficiently. A Photoelectric Sensor consists primarily of an Emitter for emitting light and a Receiver for receiving light. When emitted light is interrupted or reflected by the sensing object, it changes the amount of light that arrives at the Receiver. The Receiver detects this change and converts it to an electrical output.
There are many different styles of photoelectric sensors, but really only four basic technologies: through-beam, reflective, diffuse, and background suppression. Photoelectric sensors provide three primary methods of target detection: diffused, retro-reflective and thru-beam, with variations of each. In diffused mode sensing, sometimes called proximity mode, the transmitter and receiver are in the same housing. The photoelectric effect helped to propel the then-emerging concept of wave–particle duality in the nature of light. Light simultaneously possesses the characteristics of both waves and particles, each being manifested according to the circumstances.
Photoelectric devices can be made sensitive to certain wavelengths of incoming light and used in photographic light meters. They are also used in the reproduction of movie sound tracks. The photoelectric effect is when photons, or packets of light, are shone on metal and electrons are ejected from the surface of that metal. If the frequency (or energy) of the photon hitting the metal is below a certain value, then no electron is ejected.
