The Measurement Of Parallelism Based On Diffraction Gratings

Along with the development of science and technology, the measurement precision of the requirements of the measuring process and the simplicity of the requirements of quickness, more and more is also high. Because contact measurement method to measure things size have a higher limit, the traditional image processing methods in measuring distance of the target parallel degree, because for the target surface and image acquisition system of vertical axis not completely, so the geometric distortion, to measure precision greatly, at present, the goal for large-scale distance parallel degree deviation of the lack of a good method of inspection.In order to solve the target for large parallel to the problem of measurement, this paper designs and builds a diffraction grating by double of parallel degree testing system, and and image processing method, and the combination of the grating diffraction benchmark, through line on the geometric distortion to correct. According to measuring the size of the target with high power laser distance to choose the as a point light source, through the two pieces of orthogonal placed on the diffraction grating diffraction, produce more diffraction of parallel lines by some as a baseline. Through the camera to baseline and targets for the film to get the image processing. Measured by the technology of image processing, it is to point to will image as a carrier of information, through the analysis of the image processing for the goal to get information. In this paper the image processing method for the baseline and get the target coordinates, using the least square method of linear equations are fitting. Use the parallel degree error on the baseline in the plane of the target and the camera's distortion tilt correction factors, get to the parallel degree of the object under test measurement result. Measurement and the result shows that the method simple, accurate measurement, meet high measurement precision.This paper firstly in the parallel degree of inside and outside the existing measuring methods are compared, mainly including non-contact, non-contact and image technology, method, analyzes the method of measuring the original advantages and disadvantages, for the proposed new measuring method to lay the foundation. This system and the detection principle is introduced in detail, including the parallel degree definition and grating diffraction, double orthogonal grating diffraction theory. Then this paper introduces the measurement system device, including the device of choice and the construction of the measurement system. In the fourth chapter of the experimental analysis, including experimental device adjusting, image processing method, and the analysis of the example of measurement. Conclusion.