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Proceedings Paper

Atmospheric optical turbulence measurements in the LOTIS vacuum chamber and LOTIS collimator jitter analysis results
Author(s): Stephen A. Borota; Laurence Li; Gregor Cuzner; Sheldon B. Hutchison; Andrew Cochrane
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Paper Abstract

Lockheed Martin Space Systems Company has completed the Large Optical Test and Integration Site (LOTIS) at its Sunnyvale, CA campus. Central to the LOTIS testing facility is a 6.5-meter diameter optical collimator housed in a large, temperature controlled and vibration isolated high-vacuum chamber. A measurement has been made of the atmospheric turbulence inside the LOTIS vacuum chamber testing environment at ambient pressure and temperature near floor level where distorting turbulence may be most persistent. Turbulence is one of the many components that define the overall LOTIS Collimator optical testing capabilities at ambient air pressure. Experimental measurements have been made with a non-phase-shifting Fizeau interferometer along a 50-foot horizontal propagation path in double pass. Results presented here represent root-mean-square (RMS) wavefront error over an 18-inch aperture and the corresponding atmospheric coherence length, ro (Fried's parameter). In addition, an analysis was performed to calculate the optical line-of-sight jitter response of the LOTIS Collimator system and facility due to base-level vibration disturbances. Vibration survey measurements were made using accelerometers mounted to the vacuum chamber foundation to create a Power Spectral Density (PSD) plot of the measured seismic and vacuum chamber mechanically induced vibration disturbances. The measured PSD was used as the base input to a system-level finite element model that included the LOTIS Collimator, the Flat Mirror Positioning structure and a generic Unit Under Test all mounted on the LOTIS Vibration Isolation Bench to assess the whole system jitter response. Results presented here represent the RMS jitter in nanoradians through the optical path of the LOTIS Collimator due to base-level induced seismic and chamber mechanical vibrations.

Paper Details

Date Published: 6 May 2009
PDF: 12 pages
Proc. SPIE 7330, Sensors and Systems for Space Applications III, 733003 (6 May 2009); doi: 10.1117/12.828161
Show Author Affiliations
Stephen A. Borota, Lockheed Martin Space Systems Co. (United States)
Laurence Li, Lockheed Martin Space Systems Co. (United States)
Gregor Cuzner, Lockheed Martin Space Systems Co. (United States)
Sheldon B. Hutchison, Lockheed Martin Space Systems Co. (United States)
Andrew Cochrane, Lockheed Martin Space Systems Co. (United States)

Published in SPIE Proceedings Vol. 7330:
Sensors and Systems for Space Applications III
Joseph L. Cox; Pejmun Motaghedi, Editor(s)

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