10 September 1993 Internal laser metrology for POINTS
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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.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Martin Charles Noecker, Martin Charles Noecker, James D. Phillips, James D. Phillips, Robert W. Babcock, Robert W. Babcock, Robert D. Reasenberg, Robert D. Reasenberg, } "Internal laser metrology for POINTS", Proc. SPIE 1947, Spaceborne Interferometry, (10 September 1993); doi: 10.1117/12.155748; https://doi.org/10.1117/12.155748

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