MEASUREMENT OF SURFACE DEW BY OPTICAL SENSOR

The present work describes the design of a purely optical sensor for t he detection of surface dew. The operation of the device is based on t he frustration of total internal reflection. Constructions with conven tional optical elements and with a holographic optical element (HOE) a re discussed. The HOE is recorded by He-Ne laser and the diffraction e fficiency is measured for s and p polarizations of the reconstructing beam. Also, the sensor characteristic for various dew densities of the sensitive surface is obtained theoretically and is proved experimenta lly. The sensor may be useful for isolation control of high-voltage de vices.