Title

Characterization Of Structural Relaxation In As2Se3 For Analysis Of Lens Shape Change In Glass Press Mold Cooling And Post-Process Annealing

Keywords

Annealing; FEA; Infrared glass; Modeling; Molding; Relaxation; Structure

Abstract

This study explores the structural relaxation behavior of As 2Se3 by thermo mechanical analysis in order to characterize and eventually predict volume change in As2Se 3 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. © 2013 SPIE.

Publication Date

11-28-2013

Publication Title

Proceedings of SPIE - The International Society for Optical Engineering

Volume

8884

Number of Pages

-

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1117/12.2029283

Socpus ID

84888178258 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84888178258

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