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Proceedings Paper

Temperature-dependent refractive index measurements of L-BBH2 glass for the Subaru CHARIS integral field spectrograph
Author(s): Douglas B. Leviton; Kevin H. Miller; Manuel A. Quijada; Tyler D. Groff
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Paper Abstract

Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA’s Goddard Space Flight Center, we have made the first cryogenic measurements of absolute refractive index for Ohara L-BBH2 glass to enable the design of a prism for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) at the Subaru telescope. L-BBH2 is employed in CHARIS’s prism design for improving the spectrograph’s dispersion uniformity. Index measurements were made at temperatures from 110 to 305 K at wavelengths from 0.46 to 3.16 μm. We report absolute refractive index (n), dispersion (dn/dλ), and thermo-optic coefficient (dn/dT) for this material along with estimated single measurement uncertainties as a function of wavelength and temperature. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures within applicable ranges. This paper also speaks of the challenges in measuring index for a material which is not available in sufficient thickness to fabricate a typical prism for measurement in CHARMS, the tailoring of the index prism design that allowed these index measurements to be made, and the remarkable results obtained from that prism for this practical infrared material.

Paper Details

Date Published: 3 September 2015
PDF: 11 pages
Proc. SPIE 9578, Current Developments in Lens Design and Optical Engineering XVI, 95780J (3 September 2015); doi: 10.1117/12.2189580
Show Author Affiliations
Douglas B. Leviton, Leviton Metrology Solutions, Inc. (United States)
Kevin H. Miller, NASA Goddard Space Flight Ctr. (United States)
Manuel A. Quijada, NASA Goddard Space Flight Ctr. (United States)
Tyler D. Groff, Princeton Univ. (United States)

Published in SPIE Proceedings Vol. 9578:
Current Developments in Lens Design and Optical Engineering XVI
R. Barry Johnson; Virendra N. Mahajan; Simon Thibault, Editor(s)

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