The most popular photoelectric sensor used is the retro-reflective or reflex mode sensor. One of the advantages of the retroreflective style photoelectric sensors is the light emitter, or light source, and the receiver are in the same enclosure, thus you only have a single device to mount and wire making installation easier and faster. The output of the sensor changes state when the object blocks the light beam between the sensor and the reflector.
Photoelectric sensors have solved numerous industrial applications over the years. There are basically three different sensing modes. The first is diffuse or reflex mode, next is retro reflective, which requires a reflector, and the third is through beam, transmitted or opposed. These field devices provide an excellent means of detecting target at a distance without contacting the object. All of the sensing modes are based on the sensor’s ability to detect a change in light reaching the sensor’s receiver. In this posting, we will review the diffuse or reflex photoelectric sensor.