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Proceedings Paper

Advances in homogeneity measurement of optical glasses at the Schott 20-in. Fizeau interferometer
Author(s): Peter Hartmann; Reiner H. Mauch; Heiko Kohlmann
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Paper Abstract

The requirements on the homogeneity of optical glasses have increased significantly. Especially microlithography lens applications of extreme resolution and imaging quality have driven this development. In the past global specification of the glass homogeneity by P-V-limits was common. Now there are more specific and higher requirements on definite terms of the Zernike wavefront expansion. This new challenge initiated significant improvements at the Schott 20 inch aperture Fizeau type interferometer. While exploiting the advantages of the Carl Zeiss direct measuring type interferometer we emphasized on the reduction of background noise and systematic error constributions. Together with the increase in specifications the demand for qualified glass discs has risen sharply. This led us to the introduction of a semi-automated systems for the sample inspection at the interferometer. We have performed a series of reproduction measurements and detailed time-resolved analyses for the interesting homogeneity characteristics. The results show significant advances which have been reached both in increasing the measurement accuracy and in the production process for optical glasses of extreme homogeneity.

Paper Details

Date Published: 19 August 1996
PDF: 7 pages
Proc. SPIE 2775, Specification, Production, and Testing of Optical Components and Systems, (19 August 1996); doi: 10.1117/12.246738
Show Author Affiliations
Peter Hartmann, Schott Glaswerke (Germany)
Reiner H. Mauch, Schott Glaswerke (Germany)
Heiko Kohlmann, Schott Glaswerke (Germany)

Published in SPIE Proceedings Vol. 2775:
Specification, Production, and Testing of Optical Components and Systems
Anthony E. Gee; Jean-Francois Houee, Editor(s)

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