Patent ID: 7327441

Claim:
A distance measuring system for measuring a distance based on photodetection of an external light and an internal light by projecting a pulsed laser beam to an object to be measured and by receiving said external light reflected by the object to be measured and said internal light which is a divided part of said laser beam, comprising a laser light source for emitting said pulsed laser beam based on a light emission instruction, a photodetection element capable of receiving said external light and said internal light, an optical system where said external light and said internal light enter said photodetection element at the same time, a photodetection control unit for electrically controlling the photodetection condition of said photodetection element, and a light emission and photodetection timing control unit for issuing a ready signal based on said light emission instruction, wherein said photodetection control unit enables said photodetection element to receive a first pulsed laser beam entering after the ready signal based on the ready signal, and said light emission and photodetection timing control unit generates the ready signal before or after a time when said photodetection element receive said internal light, wherein said light emission and photodetection timing control unit issues more ready signals after the time when said photodetection element receives said internal light than the ready signals issued before the time when said photodetection element receives said internal light.