Introduction to Photoelectric Sensors

Photoelectric sensors are used in many applications and industries to provide accurate detection of objects without physical contact. In its most basic form, a photoelectric sensor can be thought of as a "limit switch-like" device, where the mechanical actuator or lever arm function is replaced by a beam of light. Photoelectric sensors operate by sensing a change in the amount of light that is either reflected or blocked by an object to be detected (target). The change in light could be the result of the presence or absence of the target, or as the result in a change of the size, shape, reflectivity or color of a target.

A photoelectric sensor can be used in applications to sense targets at distances from less than 5mm (0.2in) to over 250m (820ft). Successful sensing with a photoelectric sensor requires that the object to be detected (target) causes a sufficient change of light level detected by the sensor and that the user has a clear understanding of the sensing requirements.