Patent ID: 7474388

Claim:
A distance measuring device, comprising a light projecting unit for rotating and projecting a distance measuring light to a measurement area including an object to be measured, a reference reflection unit provided relatively movable and arranged at a known position within a scanning range so as to traverse the projected distance measuring light rotated and projected to the measurement area, a moving mechanism for supporting said reference reflection unit so that said reference reflection unit moves relative to the distance measuring light, and for movably supporting said reference reflection unit to a position deviated from a measuring direction, a photodetection unit for receiving a reflection light from the object to be measured as a reflected distance measuring light and a reflection light from said reference reflection unit as an internal reference light, and a control arithmetic unit for calculating a distance to the object to be measured based on a photodetection signal relating to the reflected distance measuring light and based on a photodetection signal relating to the internal reference light.