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.

Date Published: 5 July 2000
PDF: 8 pages
Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000); doi: 10.1117/12.390235

Published in SPIE Proceedings Vol. 4006:
Interferometry in Optical Astronomy
Pierre J. Lena; Andreas Quirrenbach, Editor(s)