26 June 2017 Preliminary results of a new proposal for objective human independent striae measurement
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Proceedings Volume 10329, Optical Measurement Systems for Industrial Inspection X; 103291I (2017); doi: 10.1117/12.2268989
Event: SPIE Optical Metrology, 2017, Munich, Germany
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.
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S. Reichel, P. Hartmann, U. Petzold, C. Lempa, "Preliminary results of a new proposal for objective human independent striae measurement", Proc. SPIE 10329, Optical Measurement Systems for Industrial Inspection X, 103291I (26 June 2017); doi: 10.1117/12.2268989; http://dx.doi.org/10.1117/12.2268989
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KEYWORDS
Glasses

Digital cameras

Image processing

Wavefront distortions

Wavefronts

Adaptive optics

Calibration

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