Article ID Journal Published Year Pages File Type
746108 Optics and Lasers in Engineering 2009 10 Pages PDF
Abstract

The speckle contrast method (SCM) and the light scattering method (LSM) are two of the most promising optical techniques for on-line surface roughness measurement of slightly-rough surface. However, due to the lack of capability in eliminating the influence from the diffuse component of scattered light, SCM and LSM are both sensitive to the variations of surface correlation length. Additionally, for LSM, the presence of speckle noise leads to fluctuations in the measuring results. To solve these problems, an approach based on the spatial-average analysis of the objective speckle pattern in the specular direction, simply called spatial-average method (SAM), is proposed. The SAM establishes the quantitative relationship between a new characteristic parameter extracted from the recorded speckle image and the rms surface roughness, eliminates to a large extent the influence of diffuse light component on the measuring results, and immunizes itself from the speckle noise. The theoretical foundation of SAM is given in details. A computer simulation is then performed to make comparisons among these three methods. Finally an experiment is presented.

Related Topics
Physical Sciences and Engineering Engineering Electrical and Electronic Engineering
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