Stress measurement of EFG sapphire using Cr3+ piezospectroscopy

Drew T. Haven; Herbert E Bates; John W. Locher; Steven A. Zanella

doi:10.1117/12.2180655

22 May 2015 Stress measurement of EFG sapphire using Cr³⁺ piezospectroscopy

Drew T. Haven, Herbert E Bates, John W. Locher, Steven A. Zanella

Proceedings Volume 9453, Window and Dome Technologies and Materials XIV; 94530M (2015) https://doi.org/10.1117/12.2180655
Event: SPIE Defense + Security, 2015, Baltimore, MD, United States

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 O^2- 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.

Citation Download Citation

Drew T. Haven, Herbert E Bates, John W. Locher, and Steven A. Zanella "Stress measurement of EFG sapphire using Cr³⁺ piezospectroscopy", Proc. SPIE 9453, Window and Dome Technologies and Materials XIV, 94530M (22 May 2015); https://doi.org/10.1117/12.2180655

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