Pepperl Fuchs Photoelectric Retro Reflective Sensors

Retroreflective sensors are photoelectric sensors. They consist of an emitter and receiver in a single housing. The light produced by the emitter is reflected back to the receiver with a reflector. Whenever this light beam is obstructed, the output signal of the sensor changes state.

The emitter and receiver are aligned in a housing such that the retroreflective sensors are easy to install. Simply position a reflector on the opposite side and align the sensor with it. The standard version featuring a polarization filter combines the installation benefits offered by the retroreflective system with the reliable detection, even of reflective objects, at long detection ranges. The retroreflective sensors for clear object detection are ideal for reliably detecting transparent objects.

A retroflective sensor emits light in various orientations, sends it to a reflector, and receives a signal back. The receiver, colocated with the emitter can sense light presence or absence in any orientation, enabling an output. Targets blocking light from the receiver can be read. Shiny targets, however, are a challenge. Light reflects off the shiny surface, mimicing the reflector, rendering the target invisible to the sensor. A polarized retroreflective sensor, however, uses polarized light as its sensing medium. The light is emitted by the sensor and directed to a reflector that can rotate the polarization by 90 degrees. The receiver, colocated with the emitter, is designed to sense light beams which are polarized 90 degrees to the plane of light sent from the emitter. Thus, only light from the emitter which has been rotated by the reflector can be read by the receiver. Light not aligned to the receiver`s polarization will be ignored. This process allows shiny objects to be read by the receiver.