Operation of the sensors is based on the principle of photoelectric scanning of special scale, connected with a measurement tip of the sensor. Radiation of a LED 1 is collimated by a lens 2 and is directed on a scale 3. The image of area of the scale is examined by CMOS array 4 and is analyzed by signal processor which calculates position of the scale.

As compared with incremental sensors, absolute sensors have a number of advantages: the absolute position of the gauge plug is determined immediately after power is on and the necessity of search of the reference mark is excluded. 

Also excluded is the probability of accumulation or loss of count pulse signals in case of  impacts, vibrations and reverse motion.