They operate on the principle that infra red light is produced from an infrared emitting diode that in turn is reflected back to a photosensor from a reflective surface.

The emitters and detectors are positioned together on the same face and located in a single package which facilitates ease of mounting. There are two distinct arrangements:-
1) Focussed assemblies which have the emitters and detectors mounted on a
converging optical axis used for detecting polished surfaces.
2) Un-focussed assemblies for sensing rough or diffused surfaces.

Reflective switches provide contactless sensing and find applications in process and industrial controls, instrumentation, office equipment and consumer goods.

A range of packages constructions are available and assemblies can be supplied with custom length flying leads with connectors if required.