Measuring-technical applications of light batteries

The use of light barriers as contactless sensors is discussed. The advantage of light barriers lies in the fact that they work faster, free of fatigue, and hence more reliably than the human eye, for special tasks and with relatively limited technical expense. One-way light barriers and reflex barriers are presented. The light beam from emitter to receiver (light beam geometry, reflection) is outlined. Ways of affecting the electromagnetic radiation (affecting beam power, wavelength, and beam direction) are discussed. The electronic signal evaluation is explained.