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Proceedings Paper

Diffractive optical element in materials testing
Author(s): Raimo Veil Johannes Silvennoinen; Kai-Erik Peiponen
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Paper Abstract

The object of this paper is to present a sensor based on diffractive optics that can be applied for the materials testing. The present sensor, which is based on the use of a computer-generated hologram (CGH) exploits the holographic imagery. The CGH-sensor was introduced for inspection of surface roughness and flatness of metal surfaces. The results drawn out by the present sensor are observed to be in accordance with the experimental data. Together with the double exposure holographic interferometry (DEHI) and digital electronic speckle pattern interferometry (DSPI) in elasticity inspection, the sensor was applied for the investigations of surface quality of opaque fragile materials, which are pharmaceutical compacts. The optical surface quality was observed to be related to the porosity of the pharmaceutical tablets. The CGH-sensor was also applied for investigations of optical quality of thin films as PLZT ceramics and coating of pharmaceutical compacts. The surfaces of PLZT samples showed fluctuations in optical curvature, and wedgeness for all the cases studied. For pharmaceutical compacts, the optical signals were observed to depend to a great extent on the optical constants of the coatings and the substrates, and in addition to the surface porosity under the coating.

Paper Details

Date Published: 29 September 1998
PDF: 6 pages
Proc. SPIE 3407, International Conference on Applied Optical Metrology, (29 September 1998); doi: 10.1117/12.323302
Show Author Affiliations
Raimo Veil Johannes Silvennoinen, Univ. of Joensuu (Finland)
Kai-Erik Peiponen, Univ. of Joensuu (Finland)


Published in SPIE Proceedings Vol. 3407:
International Conference on Applied Optical Metrology
Pramod Kumar Rastogi; Ferenc Gyimesi, Editor(s)

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