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Optische Metrologie

New interferometric technique for piston measurement in segmented mirrors

Optische Metrologie
Agusti Pinto
R&D Engineering Manager, promovierter Physiker at Sensofar Medical

Im Jahr 2003 erhielt Agustí ein Fulbright-Stipendium, um an der University of California, Irvine, Forschungen zur Phasenverschiebung bei großen segmentierten Teleskopen durchzuführen.
Seine Forschungsinteressen umfassen die optische Messtechnik und das Phasing großer segmentierter Teleskope. Sie versetzen die Sensofar-Forschungsgruppe in eine herausragende Position, um in Bezug auf Innovation und höchstes technologisches Niveau immer auf dem neuesten Stand zu bleiben.

New interferometric technique for piston measurement in segmented mirrors full article
Agustí Pintó1Ferran Laguarta1Roger Artigas2Cristina Cadevall2
1Sensofar Medical, S.L. (Spain)
2Universitat Politècnica de Catalunya (UPC) Rambla Sant Nebridi, 10, E-08222 Terrassa, Spain.
Published 4 November 2002 • Published under licence by IOP Publishing Ltd
Journal of Optics A: Pure and Applied OpticsVolume 4Number 6
Citation A Pintó et al 2002 J. Opt. A: Pure Appl. Opt. 4 S369


Present trends in the design of ground-based telescopes point towards the use of segmented primary mirrors. A major problem in this type of mirror is the achievement of proper segment positioning, as they have to be aligned with an accuracy of the order of a fraction of a wavelength for near-diffraction-limit telescope performance in the infrared. In this paper we present a new interferometric technique applied to the measurement of segment vertical misalignment (piston error) in segmented mirrors. The instrument is based on a high-aperture Michelson interferometer using a broadband light spectrum. The main innovation introduced in this instrument is the use of a novel optical fibre illumination technique that allows the system to measure piston error during the daytime with an uncertainty of 5 nm in a 30 µm range. A detailed description of the light spectrum, expected interferograms and piston extraction algorithms is presented here.

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