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Faculté des Sciences appliquées
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Master thesis and internship[BR]- Master's Thesis : Coupling of a single-mode fiber with a deformable mirror in a space-based nulling interferometer[BR]- Internship (linked to master's thesis)

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Aït Hocine, Farouk ULiège
Promotor(s) : Loicq, Jerôme ULiège
Date of defense : 7-Sep-2020/9-Sep-2020 • Permalink : http://hdl.handle.net/2268.2/10470
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Title : Master thesis and internship[BR]- Master's Thesis : Coupling of a single-mode fiber with a deformable mirror in a space-based nulling interferometer[BR]- Internship (linked to master's thesis)
Translated title : [fr] Couplage d'une fibre monomode avec un miroir déformable dans un interféromètre spatial de nulling
Author : Aït Hocine, Farouk ULiège
Date of defense  : 7-Sep-2020/9-Sep-2020
Advisor(s) : Loicq, Jerôme ULiège
Committee's member(s) : Defrere, Denis ULiège
Habraken, Serge ULiège
Collette, Christophe ULiège
Language : English
Number of pages : 108
Keywords : [fr] Space interferometry
[fr] Single mode fiber
[fr] Adaptive optics
[fr] Small Sat
Discipline(s) : Engineering, computing & technology > Aerospace & aeronautics engineering
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master en ingénieur civil en aérospatiale, à finalité spécialisée en "aerospace engineering"
Faculty: Master thesis of the Faculté des Sciences appliquées

Abstract

[fr] This master thesis is dedicated to the study of single mode fibers as spatial filter in a space-based nulling interferometer. They are used to decrease the requirements on the wavefront quality that an adaptive system needs to achieve.

In order to do so, a mathematical model of the coupling efficiency of a single mode fiber placed at the focus of a telescope was developed. The model is based on the Gaussian approximation of the fundamental mode LP_01 that is propagated in the single mode fiber. Also, the model is based on the theory of Fourier optics in order to determine the electric field at the input of the fiber. The model allows to compute the coupling efficiency for any static aberrations. Also, the point spread functions of a circular pupil subjected to different aberrations are simulated thanks to the fast fourier transform algorithm.

The study is performed in the waveband [3-7] µm in order to develop a nulling interferometer for exoplanets detections. The diffraction limited performances of the system are analysed. After that, the effect of static aberrations on the coupling efficiency is analysed. Then, the simulation of typical aberrations encountered in space is performed. They represent non common path aberrations (NCPA).

The simulation of the model proves that the coupling efficiency drops from 81.45% (diffraction limited performance) to 30 % when 120 Zernike polynomials are used to represent NCPA. In order to get a RMS wavefront error below 0.1 rad a deformable mirror capable of reproducing the first 115 Zernike polynomials is needed.


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Author

  • Aït Hocine, Farouk ULiège Université de Liège > Master ingé. civ. aérospat., à fin.

Promotor(s)

Committee's member(s)

  • Defrere, Denis ULiège Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > PSILab
    ORBi View his publications on ORBi
  • Habraken, Serge ULiège Université de Liège - ULiège > Département de physique > Optique - Hololab
    ORBi View his publications on ORBi
  • Collette, Christophe ULiège Université de Liège - ULiège > Département d'aérospatiale et mécanique > Active aerospace struct. and adv. mecha. systems
    ORBi View his publications on ORBi
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