Roughness measurement of metals using a modified binary speckle image and adaptive optics

NCUIR > Engineering College > Departmant of Mechanical Engineering > journal & Dissertation > Item 987654321/109042

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/109042

Title:	Roughness measurement of metals using a modified binary speckle image and adaptive optics
Authors:	傅尹坤;Fuh, Yiin-Kuen;Hsu, Kuo Chan;Fan, Jia Ren
Contributors:	工學院機械工程學系
Keywords:	Adaptive optics;Error correction;Fluid dynamics;Fluid flow;Image analysis;Rough surface;Roughness;Scattering;Turbulence;Turbulent flow
Date:	2012-03-01
Issue Date:	2026-04-23 15:26:41 (UTC+8)
Publisher:	Elsevier Ltd.;Elsevier Ltd
Abstract:	摘要： This paper proposes an integrated roughness measurement system that is based on adaptive optics (AO) and binary analysis of speckle pattern images. The aim of this study was to demonstrate the necessity for AO compensation in regions containing both heat and fluid flow turbulences. A speckle image was obtained by projecting a laser beam onto the specimen surface, and the laser pattern image reflected from the surface was binarized to experimentally correlate the intensity with the surface roughness. In the absence of the AO correction scheme, induced turbulences can severely increase the residual rms error from 0.14 to 1.4 μm. After a real-time closed-loop AO correction, we can reduce the wavefront root mean square (rms) error to 0.12 μm, which not only compensates for the aberration error from induced disturbances but also improves the overall performance of the optical system. In addition, an AO system having different gains was investigated, and a threshold gain value was found to be able to steadily compensate for the wavefront errors in less than 2 s. Measurement results of five steel samples having roughness ranging from 0.2 to 3.125 μm (0.3 λ and 5 λ, where λ is the diode laser wavelength) demonstrate an excellent correlation between the intensity distribution of binary images and average roughness with a correlation coefficient of 0.9982. Furthermore, the proposed AO-assisted system is in good agreement with the stylus method and less than 9.73% error values can be consistently obtained. ► Aim of this study was to display the necessity for AO compensation in regions containing both heat and fluid flow turbulences. ► In the absence of AO correction scheme, induced turbulences can severely increase the residual rms error from 0.14 to 1.4 μm. ► Adaptive optics setup is found to be essential, not only for improving the image resolution of dynamic aberration. ► Intensity distribution of binary images and average roughness with a correlation coefficient of 0.9982. 出版者： Elsevier Ltd 出版日期： 2012-03-01 出處： Optics and lasers in engineering, 2012-03, Vol.50 (3), p.312-316 資源來源： Elsevier ScienceDirect Journals Complete 版權： 2011 Elsevier Ltd 識別號： ISSN: 0143-8166 識別號： EISSN: 1873-0302 識別號： DOI: 10.1016/j.optlaseng.2011.11.003
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