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Proceedings Paper

Thermal shock testing of lapped optical glass
Author(s): Yingrui Zhang; Yuansun Wu; Han Liu; John C. Lambropoulos
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Paper Abstract

We have measured and modeled the thermal shock fracture of the commercially available BK-7 borosilicate crown optical glass as a function of surface finish prior to thermal shock testing. For surfaces lapped with alumina abrasives in the range 5 μm to 40 μm, the critical temperature drop for fracture in thin disk samples increases with diminishing abrasive size, and changes from 123.7±1.1 °C (for surfaces lapped with 40 μm abrasives) to 140.2±2.8 °C (for surfaces lapped with 5 μm abrasives.) We correlate the measured thermal shock (critical) temperature drop with the glass thermal and mechanical properties, including the fracture toughness, and the depth of surface cracks induced by the lapping process. We distinguish between "severe" and "mild" thermal shock conditions in terms of the applicable heat transfer coefficient and Biot number. We estimate that the depth of the strength controlling cracks on the edge of the disk samples was about 55-70 μm.

Paper Details

Date Published: 14 September 2007
PDF: 10 pages
Proc. SPIE 6671, Optical Manufacturing and Testing VII, 66710H (14 September 2007);
Show Author Affiliations
Yingrui Zhang, Univ. of Rochester (United States)
Yuansun Wu, Univ. of Rochester (United States)
Han Liu, Univ. of Rochester (United States)
John C. Lambropoulos, Univ. of Rochester (United States)
Lab. for Laser Energetics (United States)

Published in SPIE Proceedings Vol. 6671:
Optical Manufacturing and Testing VII
James H. Burge; Oliver W. Faehnle; Ray Williamson, Editor(s)

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