Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-11-0134
Specular Reflection based On-Machine Surface Roughness Rating of Machined Surface
1Ultraprecision machine system Lab. School of Mechanical Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
ABSTRACT
With the recent advancement in scientific foundations and technological implementation, optical metrology has become versatile problem-solving backbone in various applications especially in high precision application. Machine vision system has been widely applied to various industrial inspection applications, however, there is not only limited application for on-site inspection but many of them use complicated learning process. This study mainly concerns the surface inspection of machined metal surface using specular reflection. Machining shows a narrow but very bright specular highlight due to constant fine irregularities. As these irregularities changes in terms of surface roughness the intensity of reflected light changes. We use optical simulations to measure the irradiance as it provides fast and robust modeling of reflective and refractive freeform optics in both single-surface and segmented configurations. Machine vision was adopted and grayscale values were used to get the statistical data of images from the experiments to validate the simulation results. The highest resolution of 20nm was obtained with coincidence greater than 96% when compared to conventionally used inspection method. The proposed method is shown to be useful not only for long standoff distance and real time inspection, but also is very fast inspecting 8400mm2 area in just 3.2 seconds and robust to apply at industrial sites for real time surface inspection.
Keywords: Machine vision inspection, specular reflection, grayscale values, surface roughness
1Ultraprecision machine system Lab. School of Mechanical Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
ABSTRACT
With the recent advancement in scientific foundations and technological implementation, optical metrology has become versatile problem-solving backbone in various applications especially in high precision application. Machine vision system has been widely applied to various industrial inspection applications, however, there is not only limited application for on-site inspection but many of them use complicated learning process. This study mainly concerns the surface inspection of machined metal surface using specular reflection. Machining shows a narrow but very bright specular highlight due to constant fine irregularities. As these irregularities changes in terms of surface roughness the intensity of reflected light changes. We use optical simulations to measure the irradiance as it provides fast and robust modeling of reflective and refractive freeform optics in both single-surface and segmented configurations. Machine vision was adopted and grayscale values were used to get the statistical data of images from the experiments to validate the simulation results. The highest resolution of 20nm was obtained with coincidence greater than 96% when compared to conventionally used inspection method. The proposed method is shown to be useful not only for long standoff distance and real time inspection, but also is very fast inspecting 8400mm2 area in just 3.2 seconds and robust to apply at industrial sites for real time surface inspection.
Keywords: Machine vision inspection, specular reflection, grayscale values, surface roughness
