[en] Phase-mask coronagraphs are known to provide high contrast imaging capabilities while preserving a small inner working angle, which allows searching for exoplanets or circumstellar disks with smaller telescopes or at longer wavelengths. The AGPM (Annular Groove Phase Mask, Mawet et al. 2005[SUP]1[/SUP]) is an optical vectorial vortex coronagraph (or vector vortex) induced by a rotationally symmetric subwavelength grating (i.e. with a period smaller than λ/n, λ being the observed wavelength and n the refractive index of the grating substrate). In this paper, we present our first midinfrared AGPM prototypes imprinted on a diamond substrate. We firstly give an extrapolation of the expected coronagraph performances in the N-band (~10 μm), and prospects for down-scaling the technology to the most wanted L-band (~3.5 μm). 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, P.; Uppsala Univ. (Sweden)
Karlsson, M.; Uppsala Univ. (Sweden)
Mawet, D.; Jet Propulsion Lab. (USA)
Lenaerts, Cedric ; Université de Liège - ULiège > CSL (Centre Spatial de Liège)
Habraken, Serge ; Université de Liège - ULiège > Département de physique > Optique - Hololab - CSL (Centre Spatial de Liège)
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)
Boccaletti, A.; Observatoire de Paris à Meudon (France)
Baudrand, J.; Observatoire de Paris à Meudon (France)
Language :
English
Title :
Annular groove phase mask coronagraph in diamond for mid-IR wavelengths: manufacturing assessment and performance analysis
Publication date :
01 July 2010
Event name :
SPIE
Audience :
International
Main work title :
Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave
Mawet, D., Riaud, P., Absil, O. and Surdej, J., "Annular Groove Phase Mask Coronagraph", ApJ 633, 1191-1200 (2005).
Lyot, B., "The study of the solar corona and prominences without eclipses (George Darwin Lecture, 1939)", MNRAS 99, 580-594 (1939).
Soummer, R., Aime, C. and Falloon, P.-E., "Stellar coronagraphy with prolate apodized circular apertures", A&A 397, 1161-1172 (2003).
Kuchner, M. and Traub, W., "A Coronagraph with a Band-limited Mask for Finding Terrestrial Planets", ApJ 570, 900-908 (2002).
Roddier, F. and Roddier, C., "Stellar Coronograph with Phase Mask", PASP 109, 815-820 (1997).
Rouan, D., Riaud, P., Boccaletti, A., Clénet, Y. and Labeyrie, A., "The Four-Quadrant Phase-Mask Coronagraph. I. Principle", PASP 112, 1479-1486 (2000).
Kalas, P., Graham, J., Chiang, E., et al., "Optical Images of an Exosolar Planet 25 Light-Years from Earth", Science 322, 1345-1348 (2008).
Marois, C., Macintosh, B., Barman, T., et al., "Direct Imaging of Multiple Planets Orbiting the Star HR 8799", Science 322, 1348-1352 (2008).
Lagrange, A.-M., Gratadour, D., Chauvin, G., et al., "A probable giant planet imaged in the β Pictoris disk. VLT/NaCo deep L'-band imaging", A&A 493, L21-L25 (2009).
Mawet, D., Serabyn, E., Liewer, K., Burruss, R., Hickey, J. and Shemo, D., "The Vector Vortex Coronagraph: Laboratory Results and First Light at Palomar Observatory", ApJ 709, 53-57 (2010).
Serabyn, E., Mawet, D. and Burruss, R., "An image of an exoplanet separated by two diffraction beamwidths from a star", Nature 464, 1018-1020 (2010).
Lagrange, A.-M., Bonnefoy, M., Chauvin, G., et al., "A Giant Planet Imaged in the Disk of the Young Star β Pictoris", Science (2010); doi: 10.1126/science.1187187.
Moerchen, M., Telesco, C., De Buizer, J., Packham, C. and Radomski, J., "12 and 18 μm Images of Dust Surrounding HD 32297", ApJ 666, L109-L112 (2007).
Foo, G., Palacios, D. and Swartzlander, G., Jr., "Optical vortex coronagraph", Opt. Lett. 30, 3308-3310 (2005).
Mawet, D., Riaud, P., Surdej, J. and Baudrand, J., "Subwavelength surface-relief gratings for stellar coronagraphy", Appl. Opt. 44, 7313-7321 (2005).
Boccaletti, A., Riaud, P., Baudoz, P., et al., "The Four-Quadrant Phase Mask Coronagraph. IV. First Light at the Very Large Telescope", PASP 116, 1061-1071 (2004).
Kikuta, H., Ohira, Y. and Iwata, K., "Achromatic quarter-wave plates using the dispersion of form birefringence", Appl. Opt. 36, 1566-1572 (1997).
Riaud, P., Boccaletti, A., Rouan, D., Lemarquis, F. and Labeyrie, A., "The Four-Quadrant Phase-Mask Coronagraph. II. Simulations", PASP 113, 1145-1154 (2001).
Moharam, M. and Gaylord, T., "Diffraction analysis of dielectric surface-relief gratings," JOSA 72, 1385-1392 (1982).
Bundy, F., "Melting Point of Graphite at High Pressure: Heat of Fusion", Science 137, 1055-1057 (1962).
Gilmozzi, R. and Spyromilio, J., "The European Extremely Large Telescope (E-ELT)", The Messenger 127, 11-19 (2007).
Mawet, D. and Serabyn, E., "The vector vortex coronagraph: analysis of sensitivity to low-order aberrations, central obscuration and chromatism", Proc. SPIE 7739 (2010).
Karlsson, M. and Nikolajeff, F., "Diamond micro-optics: microlenses and antireflection structured surfaces for the infrared spectral region", Opt. Express 11, 502-507 (2003).
Karlsson, M., Vartianen, I., Kuittinen, M. and Nikolajeff, F., "Fabrication of sub-micron high aspect ratio diamond structures with nanoimprint lithography", Microelectron. Eng. (2010); doi:10.1016/j.mee. 2009.12.085.