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Hurst exponent determination for digital speckle patterns in roughness control of metallic surfaces

2010; Elsevier BV; Volume: 49; Issue: 1 Linguagem: Inglês

10.1016/j.optlaseng.2010.09.005

1873-0302

A.L. Sampaio, Diomar Cesar Lobão, L.C.S. Nunes, P. A. M. dos Santos, L. Silva, J. A. O. Huguenin,

Optical measurement and interference techniques

In this paper, we present a study of metallic surface roughness using the Hurst exponent calculated from speckle pattern. A set of samples was prepared using polishing techniques and the roughness was directly measured by means of an optical profilometer. To study the H exponent, an experiment was performed by illuminating the samples using an expanded laser beam and the surface image was captured by a CCD camera. We applied techniques of the Hurst exponent calculation, traditionally calculated from surface profile, in the digitalized speckle patterns generated by the rough surfaces. We showed a clear dependence of the H exponent on roughness of the samples. We demonstrated that this tool is very sensitive to defects in the surfaces and can be used for roughness control.