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Proceedings Paper

Internal laser metrology for POINTS
Author(s): Martin Charles Noecker; James D. Phillips; Robert W. Babcock; Robert D. Reasenberg
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Paper Abstract

We present the designs for laser distance gauges to be used in the POINTS instrument, and preliminary performance data. For the target 5 micro-arcsecond astrometric accuracy, we must hold or monitor some critical internal dimensions of the POINTS instrument with 2 picometer (pm, 10-12 m) accuracy for a few hours. The POINTS architecture makes good use of these gauges, minimizing the number and range of dimensions that must change during operation, and maximizing the similarity of the starlight and metrology measured paths. Gauge designs have been developed for both optical-path-differencing (Michelson) and point-to-point measurements (Fabry-Perot). The Michelson fringes have been measured in a differential (comparison) test; the root-two-point variance (analogous to the Allan variance) in the difference of two measurements over essentially identical 1-meter paths was about 2 pm for averaging times between 40 seconds and 6 hours. A second design for the point-to-point measurements incorporates cornercube retro-reflectors in a resonant cavity. We discuss the new problems anticipated in this design, including the problem of maintaining laser alignment in these point-to-point gauges over the +/- 3 degree range of instrument articulation.

Paper Details

Date Published: 10 September 1993
PDF: 14 pages
Proc. SPIE 1947, Spaceborne Interferometry, (10 September 1993); doi: 10.1117/12.155748
Show Author Affiliations
Martin Charles Noecker, Smithsonian Astrophysical Observatory (United States)
James D. Phillips, Smithsonian Astrophysical Observatory (United States)
Robert W. Babcock, Smithsonian Astrophysical Observatory (United States)
Robert D. Reasenberg, Smithsonian Astrophysical Observatory (United States)

Published in SPIE Proceedings Vol. 1947:
Spaceborne Interferometry
Robert D. Reasenberg, Editor(s)

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