Optical Design Of Large-sided Three-dimensional Profile Based On Principle Of Laser Ranging

Three-dimensional profile measurement technique is widely used in product development, manufacturing and testing process of CAD, CAM, reverse engineering and so on. It relates to the automotive, mold, electronic communications, aerospace and other fields. This paper is based on the principle of laser ranging, and aims at the large size target, such as the surface’s measuring of the trains and planes. Focuses on the optical design of the three-dimensional shape measurement technology. It uses double optical path comparison method ranging technology as the optical principle. The baseband of the infrared laser is from200THz to100GHz, and the wavelength is1550nm. The beam diameter is3mm and the divergence angle is10mrd. The output end of the fiber optics uses Gradient index lens to adjust the beam parallelism.Laser beam expander collimator lens uses zoom beam expander lens, and the beam expander than is4-7times for different measuring distance. Sensors selects1/3-inch high-sensitivity CCD which diagonal is6mm, and effective pixels is752*582. CCD lens uses the zoom principle to design a zoom lens which zoom range is1/2to2/7. The measuring range of the optical system is2～18m, the measurement accuracy reaches to0.2mm and the spot size is12-21mm. According to the principles of the overall system, the system meets the ranging requirements.This paper firstly makes an overall introduction of the large-size three-dimensional shape measurement technique which is based on the laser ranging principle, and then protocols the optical system principle. Focuses on the analysis of the optical system part. The optical design of the gradient refractive index lens, the beam expander laser zoom and the CCD lens is the important part. According to the actual processing craft to make a tolerance analysis for the various lens parts. At the last, gives a analysis of the sources of systematic error, and summarizes the design of the optical system.