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Proceedings Paper

Measurement of defects by measuring of light scattering from surfaces using focused illumination
Author(s): O. Rodríguez-Núñez; Neil C. Bruce
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Paper Abstract

Light scattering has been used as a method of characterizing material or surface roughness in different areas of the science and technology, usually the surface is illuminated with light and the pattern of scattering is measured above the surface. In the literature, the scattered light has been measured using an incident beam with a diameter on the order of a few cm for surfaces with roughness scales of the order of microns, mainly to avoid problems with the speckle pattern of light. However, this kind of measurement does not give information on local variations in roughness or defects present in the sample. Also, it has been reported in many studies that the polarization of the scattered light is affected by the surface material and roughness. In this paper we present a novel experimental device used to identify local defects on surfaces by the measurement of the scattered light pattern using laser light focused onto the surface. We present results of experimental measurements for two surfaces with roughness and defects of the order of 6 to 60 microns using sizes of incident beam of the same order and we compare the results of experimental cases with results of numerical calculation based on the Kirchhoff Approximation of light scattering by rough surfaces. We include preliminary results from the effect on the pattern of light scattering as a function of the polarization state by using focused light to illuminate the surface, we calculate the Mueller matrix for the equivalent period of the surface micro-manufactured experimentally. Finally we conclude about the validity of the method.

Paper Details

Date Published: 26 April 2016
PDF: 8 pages
Proc. SPIE 9890, Optical Micro- and Nanometrology VI, 989012 (26 April 2016); doi: 10.1117/12.2220422
Show Author Affiliations
O. Rodríguez-Núñez, Univ. Nacional Autónoma de México (Mexico)
Neil C. Bruce, Univ. Nacional Autónoma de México (Mexico)

Published in SPIE Proceedings Vol. 9890:
Optical Micro- and Nanometrology VI
Christophe Gorecki; Anand Krishna Asundi; Wolfgang Osten, Editor(s)

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