In many applications, optoelectronic transmitters and
receivers are used in pairs and linked together
optically. Manufacturers fabricate them in suitable
forms. They are available for a wide range of
applications as ready-to-use components known as
couplers, transmissive sensors (or interrupters),
reflex couplers and reflex sensors. Increased
automation in industry in particular has heightened the
demand for these components and stimulated the
development of new types