Laser scanning system

Abstract

A laser scanner for measuring the spatial properties of objects in a scene within a range less than a predetermined maximum object distance. A laser diode supplies a laser beam that is intensity-modulated by a reference waveform from a waveform generator. An optical scanning system scans the scene with the intensity-modulated laser beam, and receives reflected intensity-modulated light and supplies it to an optical processing system that includes an aperture that transmits a first percentage of light reflected from the maximum object distance and a second, lesser percentage of light reflected from objects closer than the maximum object distance. A photodetector receives the processed light and converts the energy into an amplitude-modulated range signal. A mixer down-converts the frequency into an IF frequency, and a first circuit converts the range signal to the form of a square wave. A phase comparator receives the processed range signal and the reference waveform and outputs a highly accurate signal indicative of the phase difference therebetween. In some embodiments a calibration target may be situated within the scene having a plurality of steps with predefined distances to use as a calibration for measurements of the spatial relationships within the scene.