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26 February 2003 Alignment of the MAM testbed to enable micro-arcsecond astrometry performance for SIM
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Future space-based optical interferometers, such as the Space Interferometer Mission, require fringe measurements at the picometer level in order to produce astrometric data at the micro-arc-second level. More specifically, both the position of the central starlight fringe and the change in the internal optical path of the interferometer must be measured to a few tens of picometers. The internal path is measured with a small metrology beam, whereas the starlight fringe position is estimated with a CCD sampling a large concentric annular beam. One major challenge for SIM is to align the metrology beam with the starlight beam to ensure consistency between these two sensors. The Micro-Arcsecond Metrology testbed (MAM) developed at the Jet Propulsion Laboratory features an optical interferometer with a white light source, all major optical components of a stellar interferometer, and heterodyne metrology sensors. The experiment is installed inside a large vacuum chamber in order to mitigate atmospheric and thermal disturbances. Both the white light and metrology sensors have been proven to work independently at the required levels. The next step is to integrate them as a micro-arc-second capable system. A complex alignment sequence has been developed in order to match the absolute tilt and shear of the metrology and starlight paths to 1 micro-radian and 10 micrometers respectively. This paper describes the MAM optical setup, the alignment process, the contribution of the fine alignment to the final performance, and how they relate to SIM.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Renaud Goullioud and Eric E. Bloemhof "Alignment of the MAM testbed to enable micro-arcsecond astrometry performance for SIM", Proc. SPIE 4852, Interferometry in Space, (26 February 2003);


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