You can use an LED as a light source, sure, but did you know you can use one as a sensor? The concept of using an LED as a sensor is much like using a speaker as a microphone. Flip things around ...

The motion sensor can be placed anywhere to control up to two rooms of lights. It has a motion detection range of about 5 meters, or 16.5 feet, so whenever anyone walks near it, lights turn on.

By integrating the image sensor with a dedicated image ... and to optimize image clarity under low light and/or short exposure times. LFM eliminates LED flicker and enhances driver safety.