Unpublished conference/Abstract (Scientific congresses and symposiums)
First manufactured diamond AGPM vector vortex for the L- and N-bands: metrology and expected performances
Delacroix, Christian; Forsberg, Pontus; Karlsson, Mikael et al.
2010In the Spirit of Lyot 2010
 

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Abstract :
[en] The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) is an optical vectorial vortex coronagraph (or vector vortex) synthesized by a circular subwavelength grating, that is a grating with a period smaller than λ/n (λ being the observed wavelength and n the refractive index of the grating substrate). Since it is a phase mask, it allows to reach a high contrast with a small working angle. Moreover, its subwavelength structure provides a good achromatization over wide spectral bands. Recently, we have manufactured and measured our first N-band prototypes that allowed us to validate the reproducibility of the microfabrication process. Here, we present newly produced mid-IR diamond AGPMs in the N-band (~10 µm), and in the most wanted L-band (~3.5 µm). We first give an extrapolation of the expected coronagraph performances. We then present the manufacturing and measurement results, using diamond-optimized microfabrication techniques such as nano-imprint lithography (NIL) and reactive ion etching (RIE). Finally, the subwavelength grating profile metrology combines surface metrology (scanning electron microscopy, atomic force microscopy, white light interferometry) with diffractometry on an optical polarimetric bench and cross correlation with theoretical simulations using rigorous coupled wave analysis (RCWA).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Delacroix, Christian  ;  Université de Liège - ULiège > Département de physique > Optique - Hololab
Forsberg, Pontus;  Uppsala University
Karlsson, Mikael;  Uppsala University
Mawet, Dimitri;  NASA/JPL
Lenaerts, Cedric ;  Université de Liège - ULiège > CSL (Centre Spatial de Liège)
Habraken, Serge ;  Université de Liège - ULiège > Département de physique > Optique - Hololab
Absil, Olivier  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Hanot, Charles ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Surdej, Jean  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Language :
English
Title :
First manufactured diamond AGPM vector vortex for the L- and N-bands: metrology and expected performances
Publication date :
28 October 2010
Event name :
In the Spirit of Lyot 2010
Event organizer :
Observatoire de Paris-Meudon
Event place :
Paris, France
Event date :
25-29 october 2010
Audience :
International
Name of the research project :
VORTEX
Available on ORBi :
since 03 April 2011

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