The optical method of measuring surface roughness was developed in the 1970s, and its feature surface of non-contact measurement has received extensive attention. Among them, light scattering is the most attractive: it has the advantages of area sampling, fast measurement speed and easy processing. For more than 20 years, scholars at home and abroad have conducted a lot of research, and instruments have entered the practical stage. At present, the methods widely used at home and abroad are the light intensity method and the light intensity ratio method. These methods have small measurement specifications: they are extremely sensitive to the position and material of the surface to be measured, and thus have weak anti-interference ability, and most of them are made of He-Ne laser. The light source makes the instrument huge and cannot be used in the processing and promotion. In the mid-1980s, the angular distribution of scattered light intensity was proposed abroad.
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