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Proceedings Paper

Numerical simulation tool for synthetic speckle pattern images and their intensity-based integration under variable conditions for metrology applications
Author(s): Falko Riechert; Georg Bastian; Uli Lemmer
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Paper Abstract

In many metrological applications speckle can be used to determine surface properties where several complex effects and parameters are of concern. However, an analytical modelling of the decorrelation of speckle patterns created e.g. by two wavelength illumination of a surface is possible only for Gaussian-distributed surface height values and in illumination regimes where the separation of the two illumination wavelengths is much smaller than the mean value of the two wavelengths. Depending on the fabrication process of the illuminated surface the statistical distribution of the surface height values can differ significantly from a Gaussian distribution. We present a numerical simulation tool for the synthetic generation of laser-speckle patterns which a non-imaging observer (e.g. a bare CCD-chip) detects in the farfield of an illuminated surface. We investigate for which illumination wavelengths separation the analytical model is valid with a centre wavelength of 650 nm and compare simulated speckle images originating from surfaces with equal- and Gaussian-distributed height values under two-wavelength illumination. We show which differences from the analytical model for the correlation of the two emerging speckle images occur and consider the implications for an experimental situation.

Paper Details

Date Published: 18 June 2007
PDF: 10 pages
Proc. SPIE 6617, Modeling Aspects in Optical Metrology, 661709 (18 June 2007); doi: 10.1117/12.726033
Show Author Affiliations
Falko Riechert, Univ. of Karlsruhe (Germany)
Georg Bastian, Univ. of Applied Sciences Trier (Germany)
Uli Lemmer, Univ. of Karlsruhe (Germany)

Published in SPIE Proceedings Vol. 6617:
Modeling Aspects in Optical Metrology
Harald Bosse; Bernd Bodermann; Richard M. Silver, Editor(s)

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