Surface Topography Measurement of Mirror-Finished Surfaces Using Fringe-Patterned Illumination

Surface Topography Measurement of Mirror-Finished Surfaces Using Fringe-Patterned Illumination
Title:
Surface Topography Measurement of Mirror-Finished Surfaces Using Fringe-Patterned Illumination
Other Titles:
Metals
Publication Date:
01 January 2020
Citation:
Fu, S.; Cheng, F.; Tjahjowidodo, T. Surface Topography Measurement of Mirror-Finished Surfaces Using Fringe-Patterned Illumination. Metals 2020, 10, 69.
Abstract:
Mirror-finished surface products have a wide range of applications in different engineering industries, such as power generation, aerospace, semiconductors and optics. The surface topography of mirror-finished products is typically measured in a metrology laboratory, which is typically time consuming and cannot be integrated into the manufacturing process. To allow for in-situ product quality assurance and automatic tool change for manufacturing processes, a more accurate and responsive surface-measurement method is needed. For highly polished surfaces, a sub-micron surface fluctuation makes it possible to use light-scattering effects and image processing for surface texture analysis. A non-contact surface inspection system using a fringe-patterned illumination method is proposed in this paper. A predesigned pattern was projected onto the target surface, and its reflected image was captured by a camera. It was found that the surface parameters Sa and Sq, which are widely used to evaluate surface quality, are significantly correlated with luminous-intensity distribution. Another parameter, Str, which quantifies the uniformity of surface-texture directions due to polishing or grinding marks, was traditionally quantified after a complete-surface topographic measurement. In this research, a new approach is proposed to determine surface isotropy through a luminance-intensity distribution analysis. By rotating the test coupon, the variation of specular reflection showed correlation with the significance of surface-texture direction. The experimental results demonstrate that mirror-finished surfaces with a large deviation in luminance intensity across the pattern possess low Str values, which indicates low uniformity in surface texture.
License type:
http://creativecommons.org/licenses/by/4.0/
Funding Info:
Description:
ISSN:
2075-4701
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