The Measurement And Experimental Research Of Optical Triangulation Methods On Metal Surface

Optical triangulation has the advantages of simple optical path,wide measurement range,high measurement accuracy,etc.It has a huge application prospect in optical non-contact measurement.In the measurement of metal surface profile,the optical triangulation method has two measurement schemes,one is the laser triangulation method represented by laser,and the other is the light section method represented by incoherence.Although the laser triangulation method measures a long distance,The measurement range is large,but its measurement accuracy is not high,and it cannot meet the high-precision measurement of the metal surface profile.Although the light section method has high measurement accuracy,the measurement distance and measurement range are very small.Therefore,the optical path built in this article wants to achieve high-precision measurement of metal surfaces at a centimeter-level measurement distance and a larger measurement range.The main tasks are as follows:(1)This article finds that the existing laser triangulation measurement accuracy on the market is not enough to complete the high-precision measurement of metal surfaces,so it is proposed to build a measurement optical system based on the principle of optical triangulation.First,two theoretical derivations of optical triangulation The mathematical model of the measurement structure selects the oblique incident optical path with high measurement resolution and good fringe quality as the optical path construction plan in this paper.The optimal measurement angle is theoretically analyzed and experimentally verified to determine the optimal measurement angle.The main optical components in the optical path are selected,and the structure of the outgoing optical path,the installation device of the object under test and the acquisition device are designed and optimized.(2)The optical acquisition system in this paper will have the problem of image distortion.In view of this problem,the built optical path system is calibrated,the image is distorted,and different filtering schemes are selected to filter the light bar,and the LED light bar built in this paper is analyzed For the grayscale distribution of the light bar,the edge extraction algorithm and the geometric center method are used to process and compare the results of the light bar.The algorithm is optimized for the problem of holes in the light bar,and the hole is filled by binarization.Extract the profile information of the light strip,calibrate the measurement system,and obtain the proportional relationship between the object images,so as to obtain the true profile height information of the surface of the measured object.(3)In order to verify the measurement accuracy of the optical path built in this article,the light section method and line laser method that belong to the principle of optical triangulation and the optical path built in this article are used to measure the topography of the metal surface.A standard metal object to be measured is required,and a planer The roughness sample is in the measurement interval of the four measurement schemes,so it is taken as the measurement object.Take the surface roughness value and profile curve as the evaluation basis,and use the measurement result of the white light interference as the benchmark to draw the measured profile curve,and calculate the surface roughness Ra and Rz values.