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6 July 1998 Subnanometer laser metrology for spacecraft interferometry
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Several proposed space-based interferometry missions require positional knowledge of their optical elements to very high precision. To achieve the desired stellar position measurement precision, the internal optical path difference of the stellar interferometer must be measured to within 10 picometers. This knowledge can be provided by a metrology system based on a laser interferometer incorporating the spacecraft optics. We present results from fabrication and testing of a lab-based frequency-modulated (FM) Michelson interferometer intended to maintain length stability to a few picometers. The instrument can be used to make precise relative distance measurements or it can be used to characterize orientation and polarization effects of system components commonly used in metrology gauges. External frequency modulation of a frequency- stabilized laser source and phase-sensitive detection are used to detect changes in the arm length difference of the interferometer. Arm length adjustments are made via a closed loop feedback system. A second system having a shared beampath with the primary system monitors the performance of the primary system. Preliminary data, operating in an ambient lab environment, demonstrate control to roughly 6 picometers rms for measurement times around 10 seconds.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
James W. Leitch, Greg A. Kopp, and Charley Noecker "Subnanometer laser metrology for spacecraft interferometry", Proc. SPIE 3479, Laser Interferometry IX: Applications, (6 July 1998);

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