Patent ID: 7333183

Claim:
A laser scanning device comprising: a light projecting part for projecting laser light to irradiate a target area scanningly in a specified orientation for carrying out distance-measuring operations; a main light receiving element for receiving reflected light of said laser light from said target area and detecting intensity of said received reflected light; an auxiliary light receiving element for receiving reflected light from a preceding area which is displaced from said target area by a specified angle and detecting intensity of reflected light from said preceding area; amplifiers for amplifying intensities detected by said main light receiving element and said auxiliary light receiving element; a gain control part for adjusting the gain of said amplifiers for the next one of said distance-measuring operations based on the intensity of said projected laser light and the intensity of reflected light detected by said auxiliary light receiving element; and a measuring part for measuring the distance to an object from said projection timing of said projected laser light and the timing of receiving reflected laser light each time said specified angle is scanned.