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Proceedings Paper

Optical glass: refractive index change with wavelength and temperature
Author(s): Marion Englert; Peter Hartmann; Steffen Reichel
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Paper Abstract

With the catalog of 1992 SCHOTT introduced two formulae each with six parameters for a better representation of the refractive index of optical glasses. The Sellmeier-equation improved the characterization of dispersion at room temperature and the Hoffmann equation that of its temperature dependence. Better representation had been expected because both formulae were derived from general dispersion theory. The original publication of Hoffmann et al. from 1992 contains first results on the accuracy of the fits. The extended use of the formulae has led to a collection of data allowing reviewing the adequacy of the Sellmeier-equation approach on a much broader basis. We compare fitted refractive index values with measured values for all wavelengths used at our precision refractive index goniometer. Data sets are available for specific melts of the four representative glass types N-BK7, N-FK5, LF5 and IRG2. For some materials, the optical glass N-LAF21, the IR glass IRG2 and the crystal CaF2, several sets of data for the temperature dependence of the refractive index are available thus giving evidence for the variation of these properties among melts of the same material.

Paper Details

Date Published: 1 May 2014
PDF: 14 pages
Proc. SPIE 9131, Optical Modelling and Design III, 91310H (1 May 2014); doi: 10.1117/12.2052706
Show Author Affiliations
Marion Englert, Hochschule Darmstadt (Germany)
Peter Hartmann, SCHOTT AG (Germany)
Steffen Reichel, Hochschule Darmstadt (Germany)
SCHOTT AG (Germany)


Published in SPIE Proceedings Vol. 9131:
Optical Modelling and Design III
Frank Wyrowski; John T. Sheridan; Jani Tervo; Youri Meuret, Editor(s)

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