sensors

The sensor senses water hitting its outer surface using beams of infrared light, modeling the principle used in automotive rain-sensing wiper controls. The optical gauge reflects infrared rays inside the sensor lens, and when raindrops hit the surface, the infrared light escapes through. Changes in the intensity of infrared rays during rain are directly correlated with the size of the raindrop. The system automatically compensates for condensation and very small drops; it can detect raindrops smaller than half a millimeter.