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Proceedings Paper

Temperature-dependent refractive index of Cleartran ZnS to cryogenic temperatures
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Paper Abstract

Cleartran® ZnS is a water clear form of CVD ZnS and a popular material for infrared optical designs. In order to enable the highest quality lens designs with this material at cryogenic temperatures, we have measured the absolute refractive indices of two prisms as a function of both wavelength and temperature using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA’s Goddard Space Flight Center (GSFC). While conventional CVD ZnS has received considerable study at cryogenic temperatures, to our knowledge, cryogenic indices of Cleartran have not been measured by other investigators. For our measurements of Cleartran, we report absolute refractive index, spectral dispersion (dn/dλ), and spectral thermo-optic coefficient (dn/dT) at temperatures ranging from 20 to 300 K at wavelengths from 0.50 to 5.6 μm. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate computation of index at any applicable wavelength and temperature. We compare our measured indices with those of the material’s manufacturer, Rohm & Haas, at room temperature where we find good agreement to within our measurement uncertainty, and we compare our refractive indices and their aforementioned derivatives to cryogenic temperatures with those for conventional ZnS from the literature

Paper Details

Date Published: 27 September 2013
PDF: 8 pages
Proc. SPIE 8863, Cryogenic Optical Systems and Instruments 2013, 886307 (27 September 2013); doi: 10.1117/12.2024817
Show Author Affiliations
Douglas B. Leviton, NASA Goddard Space Flight Ctr. (United States)
Bradley J. Frey, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 8863:
Cryogenic Optical Systems and Instruments 2013
James B. Heaney; E. Todd Kvamme, Editor(s)

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