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Proceedings Paper

Stress measurement of EFG sapphire using Cr3+ piezospectroscopy
Author(s): Drew T. Haven; Herbert E Bates; John W. Locher; Steven A. Zanella
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Paper Abstract

Sapphire’s hardness, strength, and UV-IR transmittance make it an excellent candidate for IR window and transparent armor applications. At Saint-Gobain Crystals, Edge-defined Film-fed Growth (EFG) sapphire crystals are currently being manufactured for IR window and transparent armor applications in sizes up to 305x510x11 mm. However, the demand for even larger sapphire panels continues to increase. In order to aid in the development of larger pieces, a nondestructive measurement has been developed to map planar stress in Clear Large Area Sapphire Sheet (CLASS). The measurement works by utilizing optical excitation of trace amounts of Cr3+ impurities. The resulting luminescence produces a sharp emission doublet whose exact wavelength is dependent on spacing between Cr3+ and O2- ions in sapphire, and therefore the strain in the sample. By recording several data points over an array, it is possible to construct a stress map of large sapphire sheets and gain valuable information on the growth conditions of the sapphire ribbon.

Paper Details

Date Published: 22 May 2015
PDF: 8 pages
Proc. SPIE 9453, Window and Dome Technologies and Materials XIV, 94530M (22 May 2015); doi: 10.1117/12.2180655
Show Author Affiliations
Drew T. Haven, Saint-Gobain Crystals (United States)
Herbert E Bates, Saint-Gobain Crystals (United States)
John W. Locher, Saint-Gobain Crystals (United States)
Steven A. Zanella, Saint-Gobain Crystals (United States)


Published in SPIE Proceedings Vol. 9453:
Window and Dome Technologies and Materials XIV
Brian J. Zelinski; Randal W. Tustison, Editor(s)

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