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Proceedings Paper

Fringe compensation in multiband speckle shearography using a wedge prism
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Paper Abstract

Using a multiband light source in Speckle Shearography makes dispersion effects become an issue. Since the fringe pattern of a shearographic measurement depends on the wavelength, the fringe modulation decreases if a light source with a very broad band is used. Therefore, in this paper we propose to make the fringe distance of the resulting shearogram independent of the wavelength using a dispersive optical component. To demonstrate this method, a shearing interferometer is presented, which creates a shear that is proportional to the wavelength. Provided that the object deformation along the shear is linear to the first order, the wavelength dependent shear is obtained by inserting a wedge prism into a Michelson Interferometer with the object in the input plane and the detector array in the output plane. An important prerequisite to this technique is that the refractive index of the wedge prism has a linear characteristic within the observed spectral range. Since the experimental investigations were performed with a mercury arc lamp, nBK7 is shown to be a suitable material within the range of 435 nm to 546 nm.

Paper Details

Date Published: 27 May 2003
PDF: 8 pages
Proc. SPIE 4933, Speckle Metrology 2003, (27 May 2003); doi: 10.1117/12.516581
Show Author Affiliations
Claas Falldorf, Bremer Institut fuer angewandte Strahltechnik (Germany)
Steen Gruner Hanson, Risoe National Lab. (Denmark)
Wolfgang Osten, Univ. Stuttgart (Germany)
Werner P.O. Juptner, Bremer Institut für angewandte Strahltechnik (Germany)


Published in SPIE Proceedings Vol. 4933:
Speckle Metrology 2003
Kay Gastinger; Ole Johan Lokberg; Svein Winther, Editor(s)

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