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Optical metrology

New interferometric technique for piston measurement in segmented mirrors

Optical metrology
Agusti Pinto
研发工程经理,物理学博士 at Sensofar Medical

2003 年,Agustí 获得富布赖特奖学金,在加州大学欧文分校从事大型拼合式望远镜的定相研究。
他的研究领域包括光学测量和大型拼合式望远镜的定相。他的研究工作帮助 Sensofar 在创新和最高技术水平方面始终保持领先地位。

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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