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Proceedings Paper

Temperature-dependent refractive index of CaF2 and Infrasil 301
Author(s): Douglas B. Leviton; Bradley J. Frey; Timothy J. Madison
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Paper Abstract

In order to enable high quality lens designs using calcium fluoride (CaF2) and Heraeus Infrasil 301 (Infrasil) for cryogenic operating temperatures, we have measured the absolute refractive index of these two materials as a function of both wavelength and temperature using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center. For CaF2, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 25 to 300 K at wavelengths from 0.4 to 5.6 μm, while for Infrasil, we cover temperatures ranging from 35 to 300 K and wavelengths from 0.4 to 3.6 μm. For CaF2, we compare our index measurements to measurements of other investigators. For Infrasil, we compare our measurements to the material manufacturer's data at room temperature and to cryogenic measurements for fused silica from previous investigations including one of our own. Finally, we provide temperature-dependent Sellmeier coefficients based on our measured data to allow accurate interpolation of index to other wavelengths and temperatures.

Paper Details

Date Published: 12 September 2007
PDF: 11 pages
Proc. SPIE 6692, Cryogenic Optical Systems and Instruments XII, 669204 (12 September 2007); doi: 10.1117/12.735594
Show Author Affiliations
Douglas B. Leviton, NASA Goddard Space Flight Ctr. (United States)
Bradley J. Frey, NASA Goddard Space Flight Ctr. (United States)
Timothy J. Madison, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 6692:
Cryogenic Optical Systems and Instruments XII
James B. Heaney; Lawrence G. Burriesci, Editor(s)

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