The distance measurement with the Leica DISTO™ is based on the phase measurement principle. The laser diode emits light pulses with a defined wavelength and pulse repetition frequency.
Due to the runtime difference between the internal reference path and the external measurement path, the light pulses, reflected on a target and received from the Leica DISTO™, have experienced a phase shift in relation to the light pulses received through the internal reference path. That phase difference between those two signals is proportional to the distance between instrument and target.
