Stellar Interferometry

Keywords amplitude interferometry, stellar interferometry, coherence, interferometers, beam... 

Abstract We propose a general presentation of waveguides use in the frame of high resolution imaging by stellar interferometry. Brief recalls on guiding principle are followed by the required functions to be implemented. This paper is concluded by a present status on the experimental developments. 

Keywords High resolution imaging stellar interferometry optical fibers guided and inte-... 

The effects of dispersion and birefringence on stellar interferometry will be discussed in Sections 17.2.3 and 17.2.4. New kind of fibres has been design to manage the dispersion properties using a silica / air structure. These fibres, so called Photonic Crystal Fibres, are very promising for many applications (Peyrilloux et al., 2002). 

The stellar interferometry is based on the spatial coherence analysis of the source by mixing the optical fields El, E2 collected by two or more separated telescopes (see Ch. 16). In a two telescopes configuration, the corresponding interferometric signal is given by ... 

Huss, G., Re5maud, F, Delage, L., 2001, An all guided three arms interferometer for stellar interferometry, Optics Com. 196, 55 Jeunhomme L., 1990, Single-mode fiber optics, Marcel Dekker Inc. 

To achieve the angular resolution and sensitivity required for FIRI, one can use the so-called Spectral-Spatial Interferometry, Double Fourier Modulation, multi-Fourier Transform Spectroscopy or Double Interferometry (Mariotti and Ridgway 1988 Ohta et al. 2006, 2007), as a result of a combination of two well-known techniques Stellar Interferometry and Fourier Transform Spectroscopy. 

The goal of Double Fourier Modulation is to measure the spectral and spatial characteristics of an object simultaneously and it can be understood as the combination of two well known techniques Fourier transform spectroscopy (FTS) and Stellar Interferometry. The literature regarding both FTS and Stellar Interferometry is extensive, and the concepts presented here are the ones related to the work of this Thesis. 

In Sect. 2.2 the fundamentals of Stellar Interferometry are shown. Starting with the Young s double slit experiment the interferometric observables are explained, this is, the complex visibility function. The data synthesis relevant to the work of this thesis is then presented. Finally, in Sect. 2.3 the concept of Multi-Fourier Transform Interferometry is developed. 

In this Chapter the theoretical background that led to the Double Fourier Modulation technique has been presented, this is Fourier Transform Spectroscopy and Stellar Interferometry. 

Stellar Interferometry is based on the Young s two slit experiment, where incoming light from a source falls on two apertures (or telescopes) which then are made to interfere onto a screen. The measured quantity is the complex visibility V( , v). By selecting the position of the telescopes the Mv-map is sampled. The brightness distribution on the plane of the source is recovered by Fourier transforming the complex visibility. The aperture separation, or baseline, defines the angular resolution of the interferometer. 

The Double Fourier Modulation technique is the combination of Fourier Transform Spectroscopy with Stellar Interferometry for a given interferometric baseline, one performs an FTS scan. With this technique measurements of the source brightness distribution and spectrum are performed simultaneously. 

P.R. Lawson (ed.). Principles of Long Baseline Stellar Interferometry (2000)... 

F. MiUour, All you ever wanted to know about optical long baseline stellar interferometry, but were too shy to ask your adviser. New Astron. Rev. 52(2), 177-185 (2008)... 

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