Laser scanning technique for 3D measurement

Abstract

Generation of scanning structured light is an initiative triangulation-based method for acquiring range data. Unlike traditional projection of paten diaphragm, diode laser, rotating mirror and CCD camera are employed into our device. Diode laser is modulated to emit a modulated slit laser beam. Reflected by rotating mirror, the modulated slit laser beam flashes in different frequencies and generates several new type strip structured images in sequence. The strip structured images are characterized with a new pattern code which has higher resolution, speed and robustness than simply binary code. The new, highly efficient, binary code can shorten the measuring time greatly. In order to raise the resolution, the modulated silt laser beam, reflected by rotating mirror, should scanning all the measured space for eight times. As sweeping the measured space, the scanning step of modulated slit laser beam must be synchronized with rotating mirror and CCD camera. When the scanning is completed, the CCD camera take the images and store them in image-storage timely. All these work coordinately under the control of phase-locked loop. By applying the new scanning technique, a depth image with resolution of 1/256 can be obtained in just 0.3 second.