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Proceedings Paper

A new system for cryogenic thermal expansion measurement
Author(s): Chandra S. Vikram; James B. Hadaway
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Paper Abstract

Coefficient of thermal expansion is an integral part of the performance of optical systems, especially for those which operate at cryogenic temperatures. The measurement of the coefficient of relevant materials has been of continuous interest. Besides commercial measurement sources, development of one-of-a-kind tools has always been of interest due to local needs. This paper describes one such development at the University of Alabama in Huntsville (UAH). The approach involves two vertical rods (one sample and one reference) on a flat platform. A probe bar is held horizontally atop the two samples. A temperature change will generally cause rotation of the probe bar. A mirrored surface on one end of the probe bar is used to measure the rotation using the reflection of an incident laser beam upon it. The change of the reflected beam spot position is measured by a position-sensing detector. Using other known quantities, the change determines the coefficient of thermal expansion of the sample material as a function of temperature. A parallel measurement of the rotation of the sample support platform is also performed to account for any unwanted background effects. This system has been demonstrated in a cryogenic chamber at the NASA Marshall Space Flight Center X-ray Calibration Facility (XRCF). We present the system details, achievable sensitivity, and up-to-date experimental performance.

Paper Details

Date Published: 12 December 2003
PDF: 5 pages
Proc. SPIE 5179, Optical Materials and Structures Technologies, (12 December 2003); doi: 10.1117/12.507493
Show Author Affiliations
Chandra S. Vikram, Ctr. for Applied Optics/Univ. of Alabama in Huntsville (United States)
James B. Hadaway, Ctr. for Applied Optics/Univ. of Alabama in Huntsville (United States)

Published in SPIE Proceedings Vol. 5179:
Optical Materials and Structures Technologies
William A. Goodman, Editor(s)

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