ToF (Time of flight) is a distance sensing technology. It is based on measuring the time taken by light /electromagnetic wave to travel a distance through a medium. In ToF sensors, a modulated laser beam reaches the surface of detecting object, then is reflected back to the receiver. By recording the time T, which is the time the laser beam traveled, the distance d, between ToF sensor and observed object can be calculated by : d = c×T /2, where c is the speed of light.

The ToF sensors can detect object distance accurately, and is not affected by humidity, air pressure and temperature. It is suitable for indoor and outdoor usage and therefore can be widely applied in mobile phone terminal, industrial automation, obstacle detection, automatic driving vehicle, gesture recognition and other varies scenarios.