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The line laser triangulation instrument is a non-contact dimensional measuring instrument based on the triangulation principle. With the advantages of small size, high accuracy, good stability and wide application scenarios, it is widely used in the industrial production of product surface profile inspection. The measurement uncertainty reflects the stability of the instrument measurement results, it is one of the important indicators of the line laser triangulation instrument, whose theoretical limit is determined by the speckle contrast during the test. By suppressing the speckle on the sample surface, the measurement uncertainty can be effectively reduced. In this paper, we introduce the suppression of scattering during the instrument measurement by temporal averaging method and wavelength diversity method. The paper firstly introduces the speckle theory and the principles of speckle suppression by temporal averaging and wavelength diversity, simulates and analyzes the number of superimposed average images and the speckle suppression effect in the temporal averaging and the power ratio between different wavelength light sources and the speckle suppression effect in the wavelength diversity, respectively. Then, the above methods and effects are experimentally verified by combining with the developed line laser triangulation instrument. Finally, the improved line laser triangulation instrument is compared with the measurement results of the original instrument to calculate the degree of reduction in the measurement uncertainty of the instrument. The experimental results show that the optical method can effectively suppress the sample surface speckle, reduce the measurement uncertainty of the instrument, and lay the technical foundation for the development of a higher precision laser triangulation instrument. It has important application value.
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