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Proceedings Paper

Fault detection and classification in and on transparent films by light scattering
Author(s): Christo G. Stojanoff; Andreas Ante; Johannes K. Schaller
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Paper Abstract

A setup for the detection and classification of inhomogeneities (scatterers) in and on transparent films is described. The setup involves the illumination of the film by a laser light sheet. The light scattered off the film is imaged onto two linear CCD arrays. The polarization of the illuminating laser is circular and the two orthogonal linear components are filtered in front of the two CCD arrays. The CCD arrays detect the hh- and the vv-components of the scattered light, as cross-polarized scattering can be neglected. It is shown that the ratio of these two components depends for certain scattering angles on the type of scatterer. The aim of the investigations was to distinguish between dust and bubbles, the two major fault sources in thin gelatin films, the typical substratum for photographic and holographic films. The system was tested with hollow glass spheres and ragweed pollen as test scatterers. The hollow spheres behave as bubbles in the gelatin film Pollen were chosen to represent organic particles. The experimental results prove the validity of the assumed method and show an adequate characterization of the two types of scatterers provided they are at the surface of the investigated film. Statistical analysis of the experimental data show that the characterization quality is diminished if the scatterers are embedded in a gelatin layer, as not all scattering angles are observable due to total internal reflection of the scattered light.

Paper Details

Date Published: 19 July 1996
PDF: 9 pages
Proc. SPIE 2861, Laser Interferometry VIII: Applications, (19 July 1996); doi: 10.1117/12.245171
Show Author Affiliations
Christo G. Stojanoff, Technical Univ. Aachen (Germany)
Andreas Ante, Technical Univ. Aachen (Germany)
Johannes K. Schaller, Technical Univ. Aachen (Germany)

Published in SPIE Proceedings Vol. 2861:
Laser Interferometry VIII: Applications
Ryszard J. Pryputniewicz; Gordon M. Brown; Werner P. O. Jueptner, Editor(s)

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