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Proceedings Paper

Preliminary results of a new proposal for objective human independent striae measurement
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Paper Abstract

Optical glasses with certain inner quality e.g. low striae content are essential for good optical systems. A stria is a small local change in the refractive index inside the glass resulting in a wave front distortion that can cause blurring of the image. During the production process of optical glass, striae are observed by measuring it with the so-called shadow graph method. This simple measurement displays a stria as a shadow on an observation screen. A human operator evaluates the contrast by comparing it with references. The new proposed approach uses a digital camera and image processing to measure human independent the stria level. A first repeatability measurement shows wave front deviation (maximum deviation, peak-topeak) of less than +/- 8 nm.

Paper Details

Date Published: 26 June 2017
PDF: 10 pages
Proc. SPIE 10329, Optical Measurement Systems for Industrial Inspection X, 103291I (26 June 2017); doi: 10.1117/12.2268989
Show Author Affiliations
S. Reichel, Pforzheim Univ. (Germany)
Hochschule Darmstadt (Germany)
P. Hartmann, SCHOTT AG (Germany)
U. Petzold, SCHOTT AG (Germany)
C. Lempa, Hochschule Darmstadt (Germany)
Eckelmann AG (Germany)

Published in SPIE Proceedings Vol. 10329:
Optical Measurement Systems for Industrial Inspection X
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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