see also:

time-of-flight measurements

Time-of-flight measurements use the time that light or other particles require to traverse a certain distance. In LIDAR systems and in ToF cameras, the round-trip time of reflected light is used for depth-mapping a scene. In TOF mass spectrometers the mass-to-charge ratio of ions is determined by measuring the time the ion requires to reach a detector when accelerated by a known electric field.