In brief

The optical liquid level switch uses the principle of total reflection in a prism. When the sensor is surrounded by air, there is a total reflection of the emitted light, which will be entirely reflected back to the receiver. When the sensor is wetted by the fluid, some of the light will be refracted resulting in a change in the light intensity reaching the receiver. This will be able to detect this variation and determine the output of the circuit. It finds application in pharmaceuticals, air conditioning systems, industrial compressors, food processing, hydraulics, and automotive.