Diffractive optical characteristics of nanometric surface topography generated by diamond turning

• Published in: Journal of manufacturing processes 2021-07, Vol.67, p.23-34
• Main Authors: Wu, Dongxu, Kang, Chengwei, Liang, Fusheng, Yan, Guangpeng, Fang, Fengzhou
• Format: Article
• Language: English
• Subjects: Diamond turning; Diffraction spot; Finite-difference time-domain; Optical characteristics; Surface topography
• ISSN: 1526-6125; 2212-4616
• DOI: 10.1016/j.jmapro.2021.04.012

•A novel method for analyzing diffractive optical characteristics of diamond-turned surfaces is proposed.•The height and spacing of nanometric topographical features exert different influences on diffraction spots.•A laser beam with a smaller wavelength and incident angle would induce more prominent high-order diffraction spots.•The intensity of high-order diffraction spots may increase by nearly 5 times due to the roughness change of 2 nm.•Diffraction spot observation is a promising method for the rapid evaluation of diamond-turned surfaces. High-precision optical components with nanometric surface finish can be obtained directly through single point diamond turning. However, residual cutting marks on the machined surfaces are likely to cause serious diffraction and deteriorate the optical performance of a machined component. This paper proposes a novel method for diffractive optical characterization of diamond-turned surfaces based on the vector diffraction theory. The distribution characteristics of the diffraction spots are revealed by using the finite-difference time-domain method. Simulation results supported by experimental verification demonstrate that the height and spacing of nanometric surface topography exert different influences on the intensity and angle of the diffraction spots. The intensity of high-order diffraction spots would be more prominent if a laser beam with a smaller wavelength and incident angle is used to illuminate the machined surface. Even if the areal surface roughness Sa changes less than 2 nm, the gray values of high-order diffraction spots may increase by nearly 5 times under certain conditions.