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26 February 2003 Micro-arcsecond metrology (MAM) testbed overview
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One of the most critical technology requirements for the Space Interferometry Mission is that the difference in pathlength traveled by the starlight through each arm of the instrument be known with picometers of precision. SIM accomplishes this by using an internal laser metrology system to measure the optical path traveled by the starlight. The SIM technology program has previously demonstrated laser gauges with measurement accuracy below 10 picometers. The next challenge is to integrate one of these gauges into a full interferometer system and demonstrate that the system still operates at the required level. For SIM, the ultimate requirement is that the internal metrology system be able to give an accurate measure of the starlight internal path difference to about 150 picometers over its narrow-angle field, with a goal of 50 picometer accuracy. This accuracy must be maintained even as SIM's various active systems articulate the SIM optics and vary the SIM internal pathlengths. The Microarcsecond Metrology Testbed (MAM) is a full single-baseline interferometer coupled with a precision pseudostar, intended to demonstrate the level of agreement between starlight and metrology phase measurements needed to make microarcsecond-level measurements of stellar positions. MAM has been under development for several years and is now producing picometers-level consistency that translates into microarcseconds-level performance. This paper will present an overview of the MAM Testbed, together with recent results targeting the 150 picometer performance level required by SIM.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Braden E. Hines, Charles E. Bell, Renaud Goullioud, Robert Spero, Gregory W. Neat, TsePyng Janice Shen, Eric E. Bloemhof, Michael Shao, Joseph Catanzarite, Martin W. Regehr, and R. Machuzak "Micro-arcsecond metrology (MAM) testbed overview", Proc. SPIE 4852, Interferometry in Space, (26 February 2003);

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