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Proceedings Paper

Measurement and modeling of the thermal behavior of a laboratory DASH interferometer
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Paper Abstract

A Doppler Asymmetric Spatial Heterodyne (DASH) interferometer is a device that is suited to making line-of-sight measurements of thermospheric wind speeds from either ground- or space-based platforms. However, DASH interferometer characteristics are sensitive to temperature changes. These instrument changes can be tracked with calibration sources and subsequently corrected during data analysis. Even though these thermal effects can be corrected, a quantitative understanding of the physics driving them is important for future instrument designs. A previous study of the thermal behavior of a monolithic DASH system [Harlander et al, Opt. Express, 2010] measured a thermal response that was not consistent with a simplified model. It was suggested that this discrepancy was a result of the rotation of various optical components caused by the thermoelastic distortion of the monolithic interferometer elements which were cemented together yet had different coefficients of thermal expansion. This distortion effect was not included in the simplified model. In this study we assemble an interferometer with separate optical components which are allowed to expand independently with changes in temperature and therefore eliminates any distortion due to stresses induced by different coefficients of thermal expansion. Thus, by measuring the thermally induced change to the interference pattern generated by this interferometer, we may characterize the thermal behavior of the system and verify whether all the relevant physics is included in the simplified model. We find that the thermal drift measured by the experimental interferometer closely matches that predicted by the model. This important result will help in the material selection and overall design of future monolithic interferometers.

Paper Details

Date Published: 13 September 2012
PDF: 7 pages
Proc. SPIE 8493, Interferometry XVI: Techniques and Analysis, 849302 (13 September 2012); doi: 10.1117/12.928984
Show Author Affiliations
Kenneth D. Marr, U.S. Naval Research Lab. (United States)
Christoph R. Englert, U.S. Naval Research Lab. (United States)
John M. Harlander, St. Cloud State Univ. (United States)

Published in SPIE Proceedings Vol. 8493:
Interferometry XVI: Techniques and Analysis
Joanna Schmit; Katherine Creath; Catherine E. Towers; Jan Burke, Editor(s)

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