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Updated: Jul 10, 2026

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique
Published on: November 3, 2017
Thermo-optic coefficient of barium gallogermanate glass
Shyam S Bayya1, Geoffrey D Chin, Jasbinder S Sanghera
1Code 5606, Optical Sciences Division, Naval Research Laboratory, 4555 Overlook Avenue, S.W., Washington, D.C. 20375, USA. shyam.bayya@nrl.navy.mil
Abstract:
Barium gallogermanate (BGG) glasses are currently being explored as a viable low cost material for numerous U.S. defense and commercial visible-infrared window applications. These glasses are transparent from 0.4 mum to beyond 5.0 mum and can be easily made in large optics and complex shapes with high index homogeneity. For high-energy laser (HEL) applications, knowledge of the thermo-optic coefficient (dn/dT) of the window material is important in determining the optical path distortion. The dn/dT measurements were made on BGG glass at 633 and 3390 nm and compared with the values for multispectral ZnS. The dn/dT for BGG glass was approximately 1/5 the value for multispectral ZnS, giving BGG glass a clear advantage for HEL applications.
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