5 July 2000 Absolute metrology for the Very Large Telescope Interferometer (VLTI)
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The Phase Reference Imaging and Micro-arcsecond Astrometry facility (PRIMA) requires an accurate metrology system to measure the internal optical path difference (OPD) with an accuracy to 5 nm over the baseline length of the telescopes (up to 130 m). The actual concept of PRIMA plans to use an incremental metrology for measuring the internal OPD, combined with a zero-OPD calibration. As a future improvement of the PRIMA Laser Metrology System, we propose in this paper an absolute metrology system based on multiple-wavelength interferometry. It could reduce the complexity of the internal optical path calibration scheme and lead to an accurate determination of the baseline length, thus increasing the overall performance of PRIMA.
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Yves Salvade, Yves Salvade, Alain Courteville, Alain Courteville, Rene Daendliker, Rene Daendliker, } "Absolute metrology for the Very Large Telescope Interferometer (VLTI)", Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000); doi: 10.1117/12.390235; https://doi.org/10.1117/12.390235

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