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26 August 2013 Optical and thermal properties of spinel with revised (increased) absorption at 4 to 5 μm wavelengths and comparison with sapphire
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Abstract
Infrared absorption of high-quality, commercial, polycrystalline MgAl2O4 spinel is ∼40% greater in the range of 3.8 to 5.0 μm than the value predicted by the computer code OPTIMATR®, which has been used for window and dome design for more than 20 years. As a result, spinel and a -plane sapphire windows designed to support the same external pressure with the same probability of survival have approximately the same infrared absorptance in the range 3.8 to 5.0 μm. c -Plane sapphire has greater absorptance than spinel in the range 3.8 to 5.0 μm. Spinel has two weak absorption bands near 1.8 and 3.0 μm. At 1.064 μm, the laser calorimetric absorption coefficient of spinel is 10 to 50 times greater than that of sapphire. New measurements of specific heat capacity, thermal expansion, thermal conductivity, elastic constants, and refractive index (including dn/dT) of spinel are reported.
CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Daniel C. Harris, Linda F. Johnson, Robert Seaver, Tod Lewis, Giorgio Turri, Michael A. Bass, David E. Zelmon, and Nicholas Haynes "Optical and thermal properties of spinel with revised (increased) absorption at 4 to 5 μm wavelengths and comparison with sapphire," Optical Engineering 52(8), 087113 (26 August 2013). https://doi.org/10.1117/1.OE.52.8.087113
Published: 26 August 2013
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Cited by 41 scholarly publications.
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KEYWORDS
Spinel

Absorption

Sapphire

Calorimetry

Transmittance

Refractive index

Thermography

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