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Développement et validation d'un analyseur de surface d'onde en plan focal pour un instrument multi-pupilles

Abstract : The resolution of a telescope is ultimately limited by its aperture diameter, but the size of mirrors is bounded by current technology to about 10m on the ground and to a few meters in space. To overcome this limitation, interferometry consists in making an array of sub-apertures interfere; the resulting instrument is called an interferometer or a multi-aperture telescope. To reach the diffraction limit of such instruments, all sub-apertures must be phased to within a small fraction of wavelength. A critical sub-system of interferometers is the Cophasing Sensor (CS), whose goal is to measure the relative positioning errors between the sub-apertures (differential piston, tip and tilt), which are the specific low-order aberration of an interferometer and the main source of wave-front degradation. We aim to develop unsupervised and easy-to-implement CSs for the global multi-aperture telescope alignment. ELASTIC algorithm provides a solution for large amplitude tip/tilt error measurement from a modified cross-spectrum of two diversity images, allowing the geometrical alignment. ELASTIC also provides tip/tilt stability for the large amplitude piston error minimization, called the interferometric alignment. Finally a second algorithm called LAPD uses focal and slightly defocused images for the small amplitude piston/tip/tilt error measurement, allowing the fine phasing. Numerical simulations of several types of multi-aperture telescopes are performed in order to test our algorithms. We experimentally demonstrate the efficiency of the different algorithms on a 6-sub-aperture instrument. These algorithms should simplify the design of the future telescopes.
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  • HAL Id : tel-01725155, version 1

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Sébastien Vievard. Développement et validation d'un analyseur de surface d'onde en plan focal pour un instrument multi-pupilles. Optique [physics.optics]. Université Pierre et Marie Curie - Paris VI, 2017. Français. ⟨NNT : 2017PA066327⟩. ⟨tel-01725155⟩

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