Polarized light scattering measurement of metal surface roughness

• Main Authors: Kai-Ping Wang, 王凱平
• Other Authors: Cheng-Yang Liu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/28164545174167302676

碩士 === 淡江大學 === 機械與機電工程學系碩士班 === 100 === The thesis is mainly the application of techniques of polarized light scattering measurement to analyze the metal surface roughness to replace the traditional contact measurement, which can improve the speed and accuracy of the roughness measurement. The system we design for the thesis is non-contact measurement; therefore, it will not hurt the surface. Furthermore, it has advantages of high convenience, low prices of equipment, and so on. The measurement system uses a high collimated green laser irradiation on the metal surface. It measures the surface roughness scattering light distribution by the CCD camera. With calculations of the grayscale images measured by different angles, we will be able to learn about the relationship between scattered light and surface roughness. In this thesis, we conduct the experiment by using six standard specimens of metal surface roughness, the roughness (Ra) of which are respectively 0.05 μm, 0.1 μm, 0.2 μm, 0.4 μm, 0.8 μm, and 1.6 μm. We use a computer program to analyze the distribution of light intensity, which are calculated by different polarized light sources. The result shows great correlation with the metal surface roughness Ra, and then we compare the result with the images measured by metallurgical microscope. In addition, in order to understand the situation of the whole scattering light field, in this paper we also use FDTD method to simulate scattering light fields of metal surface roughness. As a result, the non-contact surveying instrument of surface scattering light that we construct for the thesis is able to measure and assess the roughness of surface of precision machinery and optical components.