Study On The Optical Design Of One Three-dimensional Shape Inspection System

Pipeline has increasingly become a primary conveying equipment for oil and nature gas because of its characteristics such as security, saving and efficiency. So, it is also broadly used in the agriculture and other industry in nowadays. As the transporting objects may have erosion, and part of the pipeline will be placed underground for a long time to work, pipeline could be damaged in the bad environment so as to lead a leakage accident. Thus, regular inspection and maintenance for pipeline is of great significance to safe operation.Based on the actual requirement of pipeline inspection and maintenance, this work is conducted mainly around a three-dimensional topography detection. An optical system to inspect pipeline is designed. It is combined binocular stereo vision and structured light. An industrial oil pipe with large diameter is chosen as inspecting object. For3D topography inspection of its inner surface, some in-depth studies are made in such ways of theory, method and experiment that the subjects of optical design, as well as its realization, measuring calibration, and so on, are accomplished.At present, frequently-used three-dimensional topography detection system has a blocking more or less, which results in ’blind spot’ or ’blind zone’. To avoid the information loss in three-dimensional topography, the inspecting optical system is configured with dual detector (CMOS). Meanwhile, according to the characteristics of pipeline and design of inspection system, a vertical arrangement of camera and laser projection is selected within a limited space. This configuration keeps a little size at lateral direction and a compact sensor for structured light. On the basis of mathematical model of structured light and vision camera detecting principle in circular structured light, a solution to meet the system calibration is devised. It is simple and convenient. In this solution, the calibration of structured light and camera calibration can be done synchronously.Finally, an experimental system is set up by means of current platform. Experimental results show that the proposed detection system is feasible, which successfully shoots a good circle strip of distortion. After digital image processing, a full message of three-dimensional morphology from pipe inner surface is obtained. It agrees with the desired effect in practice.