Fringe tracking in optical interferometry: a robust control framework for higher sensitivity limits

Jean-Pierre Folcher; Romain Petrov; Thami El Halkouj

doi:10.1117/12.2055955

24 July 2014 Fringe tracking in optical interferometry: a robust control framework for higher sensitivity limits

Jean-Pierre Folcher, Romain Petrov, Thami El Halkouj

Proceedings Volume 9146, Optical and Infrared Interferometry IV; 91461I (2014) https://doi.org/10.1117/12.2055955
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

Fringe tracking (FT) is the adaptive optics component of an Optical Long Baseline Interferometer (OLBIN). It is a critical element in particular for high spectral resolution spectro-interferometric observations. The FT must be accurate and stable, which implies high frequency sampling of the optical path differences introduced by the atmosphere and the interferometer vibrations. It must also be as sensitive as possible, which needs to minimize this sampling frequency. The optimum between these contradictory requirements must be maintained through atmospheric and instrument conditions that change very rapidly. We describe a control framework to face this robustness challenge. First, we approximate the sampled-data feedback system as a discrete time feedback system and we show that the closed-loop FT behavior is entirely determined by key closed-loop transfer functions. To fix the closed-loop bandwith in order to limit the loss of vadidity of the discrete time feedback system, we propose a loop shaping control method based on H_∞ optimization. This H_∞ framework allows to bound the frequency response of the key closed-loop transfer function. First numerical experiments are presented showing satisfactory performance when the sampling frequency disminishes. Extensive simulations to demonstate the effectivness of the proposed approach are in progress. Open issues and perspectives of applicative and/or theoretical interests are discussed.

Citation Download Citation

Jean-Pierre Folcher, Romain Petrov, and Thami El Halkouj "Fringe tracking in optical interferometry: a robust control framework for higher sensitivity limits", Proc. SPIE 9146, Optical and Infrared Interferometry IV, 91461I (24 July 2014); https://doi.org/10.1117/12.2055955

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
11 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Interferometers

Fourier transforms

Adaptive optics

Control systems

Interferometry

Optical tracking

Sensors

Show All Keywords

Keywords/Phrases

Search In:

Publication Years