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Proceedings Paper

Characterization of structural relaxation in As2Se3 for analysis of lens shape change in glass press mold cooling and post-process annealing
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Paper Abstract

This study explores the structural relaxation behavior of As2Se3 by thermo mechanical analysis in order to characterize and eventually predict volume change in As2Se3 upon relaxation during cooling after precision glass molding (PGM) and annealing. A vertical beam of As2Se3 was placed in a thermo mechanical analyzer (TMA) and fully relaxed at a given temperature. The temperature was then quickly changed a given amount and the 1-D relaxation of the beam was measured until it reached equilibrium at the new temperature. The resultant curve was then fit with a Prony series which captured the relaxation data. The mathematical representation of the relaxation is then analyzed as a function of time, temperature, and quench rate and can be used to predict one dimensional (1-D) length change upon relaxation. A maximum of three terms is needed to describe the relaxation behavior and that number declines with an increase in temperature. This decay of the number of Prony terms needed to describe relaxation points to a structure that relaxes with less complexity as it approaches Tg. These trends can be converted to 3-D due to the amorphous and therefore typically isotropic nature of As2Se3 glass. This volume change information as a function of vital processing parameters can then be used to predict the change in shape of a work piece during cooling or post process annealing within a precision molding cycle. The mathematical representation of volume relaxation can then be applied to finite element models (FEM) of As2Se3 lenses or other optical elements.

Paper Details

Date Published: 15 October 2013
PDF: 6 pages
Proc. SPIE 8884, Optifab 2013, 888416 (15 October 2013); doi: 10.1117/12.2029283
Show Author Affiliations
Erick Koontz, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Clemson Univ. (United States)
Peter Wachtel, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Clemson Univ. (United States)
J. David Musgraves, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Clemson Univ. (United States)
IRradiance Glass, Inc. (United States)
Kathleen Richardson, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Clemson Univ. (United States)


Published in SPIE Proceedings Vol. 8884:
Optifab 2013
Julie L. Bentley; Matthias Pfaff, Editor(s)

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