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1. A diamond AGPM coronagraph for VISIR

Author

Delacroix, Christian, Absil, Oliver, Mawet, Dimitri, Hanot, Charles, Karlsson, Mikael, Forsberg, Pontus, Pantin, Eric, Surdej, Jean, and Habraken, Serge

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

In recent years, phase mask coronagraphy has become increasingly efficient in imaging the close environment of stars, enabling the search for exoplanets and circumstellar disks. Coronagraphs are ideally suited instruments, characterized by high dynamic range imaging capabilities, while preserving a small inner working angle. The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) consists of a vector vortex induced by a rotationally symmetric subwavelength grating. This technique constitutes an almost unique solution to the achromatization at longer wavelengths (mid-infrared). For this reason, we have specially conceived a mid-infrared AGPM coronagraph for the forthcoming upgrade of VISIR, the mid-IR imager and spectrograph on the VLT at ESO (Paranal), in collaboration with members of the VISIR consortium. The implementation phase of the VISIR Upgrade Project is foreseen for May-August 2012, and the AGPM installed will cover the 11-13.2 {\mu}m spectral range. In this paper, we present the entire fabrication process of our AGPM imprinted on a diamond substrate. Diamond is an ideal material for mid-infrared wavelengths owing to its high transparency, small dispersion, extremely low thermal expansion and outstanding mechanical and chemical properties. The design process has been performed with an algorithm based on the rigorous coupled wave analysis (RCWA), and the micro-fabrication has been carried out using nano-imprint lithography and reactive ion etching. A precise grating profile metrology has also been conducted using cleaving techniques. Finally, we show the deposit of fiducials (i.e. centering marks) with Aerosol Jet Printing (AJP). We conclude with the ultimate coronagraph expected performances., Comment: 9 pages

Published
2014
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2. Annular Groove Phase Mask coronagraph in diamond for mid-IR wavelengths: manufacturing assessment and performance analysis

Author

Delacroix, Christian, Forsberg, Pontus, Karlsson, Mikael, Mawet, Dimitri, Lenaerts, Cédric, Habraken, Serge, Hanot, Charles, Surdej, Jean, Boccaletti, Anthony, and Baudrand, Jacques

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

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) is an optical vectorial vortex coronagraph (or vector vortex) induced by a rotationally symmetric subwavelength grating (i.e. with a period smaller than {\lambda}/n, {\lambda} being the observed wavelength and n the refractive index of the grating substrate). In this paper, we present our first mid- infrared AGPM prototypes imprinted on a diamond substrate. We firstly give an extrapolation of the expected coronagraph performances in the N-band (~10 {\mu}m), and prospects for down-scaling the technology to the most wanted L- band (~3.5 {\mu}m). 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)., Comment: 10 pages

Published
2014
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3. Deep near-infrared interferometric search for low-mass companions around beta Pictoris

Author

Absil, Olivier, Bouquin, Jean-Baptiste Le, Lebreton, Jeremy, Augereau, Jean-Charles, Benisty, Myriam, Chauvin, Gael, Hanot, Charles, Merand, Antoine, and Montagnier, Guillaume

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Aims. We search for low-mass companions in the innermost region (<300 mas, i.e., 6 AU) of the beta Pic planetary system. Methods. We obtained interferometric closure phase measurements in the K-band with the VLTI/AMBER instrument used in its medium spectral resolution mode. Fringe stabilization was provided by the FINITO fringe tracker. Results. In a search region of between 2 and 60 mas in radius, our observations exclude at 3 sigma significance the presence of companions with K-band contrasts greater than 5e-3 for 90% of the possible positions in the search zone (i.e., 90% completeness). The median 1-sigma error bar in the contrast of potential companions within our search region is 1.2e-3. The best fit to our data set using a binary model is found for a faint companion located at about 14.4 mas from beta Pic, which has a contrast of 1.8e-3 \pm 1.1e-3 (a result consistent with the absence of companions). For angular separations larger than 60 mas, both time smearing and field-of-view limitations reduce the sensitivity. Conclusions. We can exclude the presence of brown dwarfs with masses higher than 29 Mjup (resp. 47 Mjup) at a 50% (resp. 90%) completeness level within the first few AUs around beta Pic. Interferometric closure phases offer a promising way to directly image low-mass companions in the close environment of nearby young stars., Comment: 5 pages, 4 figures. Accepted for publication in A&A Letters

Published
2010
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4. Companion search around beta Pictoris with the newly commissioned L'-band vector vortex coronagraph on VLT/NACO

Author

Mawet, Dimitri, Absil, Olivier, Milli, Julien, Baudoz, Pierre, Boccaletti, Anthony, Chauvin, Gaël, Delacroix, Christian, Girard, J. H. V., Lagrange, Anne-Marie, O'Neal, Jared, Bourget, P., Forsberg, Pontus, Gonté, Frédéric, Habraken, Serge, Hanot, Charles, Karlsson, Mikael, Kasper, Markus E., Lizon, Jean-Louis, Muzic, Koraljka, Olivier, Richard, Peña, Eduardo, Slusarenko, Nicolas, Tacconi-Garman, Lowell E., Surdej, Jean, Matthews, Brenda C., Graham, James R., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Haute résolution angulaire en astrophysique, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

5. Extra-solar planet imaging: ground vs space based coronagraphs

Author

Hanot, Charles, Absil, Olivier, Boccaletti, Anthony, Vérinaud, Christophe, Surdej, Jean, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2010

6. Infrared Imaging

Author

Danchi, William, Lawson, Peter, Absil, Olivier, Hanot, Charles, Mawet, Dimitri, Lawson, P. R., Traub, W. A., and Unwin, S. C.

Subjects
Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

A mid‐infrared mission would enable the detection of biosignatures of Earth‐like exoplanets around more than 150 nearby stars. The mid‐infrared spectral region is attractive for characterizing exoplanets because contrast with the parent star brightness is more favorable than in the visible (10 million vs. 10 billion), and because mid‐infrared light probes deep into a planet’s troposphere. Furthermore, the mid‐infrared offers access to several strong molecular features that are key signs of life, and also provides a measure of the effective temperature and size of a planet. Taken together, an infrared mission plus a visible one would provide a nearly full picture of a planet, including signs of life; with a measure of mass from an astrometric mission, we would have a virtually complete picture. A small infrared mission would have several telescopes that are rigidly connected, with a science return from the detection and characterization of super‐Earth sized to larger planets near the HZ, plus a direct measure of the exozodi brightness in the HZ. In a large infrared mission, with formation‐flying telescopes, planets from an Earth‐twin and upwards in mass could be detected and characterized, as well as the exozodi. If proceeded by an astrometric mission, the detection phase could be skipped and the mission devoted to characterization, as in the visible case; lacking an astrometric mission, an infrared one could proceed alone, as was discussed for a visible coronograph, and with similar caveats. The technology needed for a large formation‐flying mission is similar to that for a small connected‐element one (e.g., cryogenics and detectors), with the addition of formation-flying technology. The technology is now in hand to implement a probe‐scale mission; starlight suppression has even been demonstrated to meet the requirements of a flagship mission. However, additional development of formation‐flying technology is needed, particularly in‐space testing of sensors and guidance, navigation, and control algorithms.

Published
2009

7. High Contrast Imaging with the New Vortex Coronagraph on NACO

Author

Mawet, Dimitri, Absil, Olivier, Girard, Julien, O’Neal, Jared, Delacroix, Christian, Baudoz, Pierre, Boccaletti, Anthony, Bourget, Pierre, Christiaens, Valentin, Forsberg, Pontus, Gonté, Frederic, Habraken, Serge, Hanot, Charles, Karlsson, Mikael, Kasper, Markus, Lagrange, Anne-Marie, Lizon, Jean-Louis, Muzic, Koraljka, Peña, Eduardo, Olivier, Richard, Slusarenko, Nicolas, Tacconi-Garman, Lowell, Surdej, Jean, Mawet, Dimitri, Absil, Olivier, Girard, Julien, O’Neal, Jared, Delacroix, Christian, Baudoz, Pierre, Boccaletti, Anthony, Bourget, Pierre, Christiaens, Valentin, Forsberg, Pontus, Gonté, Frederic, Habraken, Serge, Hanot, Charles, Karlsson, Mikael, Kasper, Markus, Lagrange, Anne-Marie, Lizon, Jean-Louis, Muzic, Koraljka, Peña, Eduardo, Olivier, Richard, Slusarenko, Nicolas, Tacconi-Garman, Lowell, and Surdej, Jean

Published
2013

8. Design, manufacturing, and performance analysis of mid-infrared achromatic half-wave plates with diamond subwavelength gratings

Author

Delacroix, Christian, Forsberg, Pontus, Karlsson, Mikael, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Surdej, Jean, Habraken, Serge, Delacroix, Christian, Forsberg, Pontus, Karlsson, Mikael, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Surdej, Jean, and Habraken, Serge

Abstract

In this paper, we present a solution for creating robust monolithic achromatic half-wave plates (HWPs) for the infrared, based on the form birefringence of subwavelength gratings (SWGs) made out of diamond. We use the rigorous coupled wave analysis to design the gratings. Our analysis shows that diamond, besides its outstanding physical and mechanical properties, is a suitable substrate to manufacture mid-infrared HWPs, thanks to its high refractive index, which allows etching SWGs with lower aspect ratio. Based on our optimized design, we manufactured a diamond HWP for the 11-13.2 mu m region, with an estimated mean retardance similar to 3.143 +/- 0.061 rad ( 180.08 +/- 3.51 degrees). In addition, an antireflective grating was etched on the backside of the wave plate, allowing a total transmittance between 89% and 95% over the band.

Published
2012
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9. Etching High Aspect Ratio Optical Gratings in Diamond

Author

Forsberg, Pontus, Delacroix, Christian, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Habraken, Serge, Surdej, Jean, Karlsson, Mikael, Forsberg, Pontus, Delacroix, Christian, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Habraken, Serge, Surdej, Jean, and Karlsson, Mikael

Published
2012

10. Development of diamond AGPM coronagraphs for VISIR and NACO

Author

Delacroix, Christian, Habraken, Serge, Karlsson, Mikael, Absil, Olivier, Hanot, Charles, Surdej, Jean, Mawet, Dimitri, Delacroix, Christian, Habraken, Serge, Karlsson, Mikael, Absil, Olivier, Hanot, Charles, Surdej, Jean, and Mawet, Dimitri

Published
2012

11. Fabricating an annular groove phase mask in diamond

Author

Forsberg, Pontus, Delacroix, Christian, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Habraken, Serge, Surdej, Jean, Karlsson, Mikael, Forsberg, Pontus, Delacroix, Christian, Mawet, Dimitri, Absil, Olivier, Hanot, Charles, Habraken, Serge, Surdej, Jean, and Karlsson, Mikael

Published
2012

12. Taking the vector vortex coronagraph to the next level for ground- and space-based exoplanet imaging instruments: review of technology developments in the USA, Japan, and Europe

Author

Mawet, Dimitri, Murakami, Naoshi, Delacroix, Christian, Serabyn, Eugene, Absil, Olivier, Baba, Naoshi, Baudrand, Jacques, Boccaletti, Anthony, Burruss, Rick, Chipman, Russell, Forsberg, Pontus, Habraken, Serge, Hamaguchi, Shoki, Hanot, Charles, Ise, Akitoshi, Karlsson, Mikael, Kern, Bryan, Krist, John, Kuhnert, Andreas, Levine, Marie, Liewer, Kurt, McClain, Stephen, McEldowney, Scott, Mennesson, Bertrand, Moody, Dwight, Murakami, Hiroshi, Niessner, Albert, Nishikawa, Jun, O’Brien, Nada, Oka, Kazuhiko, Park, Peggy, Piron, Pierre, Pueyo, Laurent, Riaud, Pierre, Sakamoto, Moritsugu, Tamura, Motohide, Trauger, John, Shemo, David, Surdej, Jean, Tabiryan, Nelson, Traub, Wesley, Wallace, James, Yokochi, Kaito, Mawet, Dimitri, Murakami, Naoshi, Delacroix, Christian, Serabyn, Eugene, Absil, Olivier, Baba, Naoshi, Baudrand, Jacques, Boccaletti, Anthony, Burruss, Rick, Chipman, Russell, Forsberg, Pontus, Habraken, Serge, Hamaguchi, Shoki, Hanot, Charles, Ise, Akitoshi, Karlsson, Mikael, Kern, Bryan, Krist, John, Kuhnert, Andreas, Levine, Marie, Liewer, Kurt, McClain, Stephen, McEldowney, Scott, Mennesson, Bertrand, Moody, Dwight, Murakami, Hiroshi, Niessner, Albert, Nishikawa, Jun, O’Brien, Nada, Oka, Kazuhiko, Park, Peggy, Piron, Pierre, Pueyo, Laurent, Riaud, Pierre, Sakamoto, Moritsugu, Tamura, Motohide, Trauger, John, Shemo, David, Surdej, Jean, Tabiryan, Nelson, Traub, Wesley, Wallace, James, and Yokochi, Kaito

Published
2011
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14. Development of a CELestial Infrared Nuller Experiment (CELINE) for broadband nulling and new single-mode fiber testing

Author

Danchi, William C., Delplancke, Françoise, Rajagopal, Jayadev K., Hanot, Charles, Riaud, Pierre, Mawet, Dimitri, Absil, Olivier, Surdej, Jean, Habraken, Serge, Danchi, William C., Delplancke, Françoise, Rajagopal, Jayadev K., Hanot, Charles, Riaud, Pierre, Mawet, Dimitri, Absil, Olivier, Surdej, Jean, and Habraken, Serge

Abstract

The small angular distance (<100 mas) and the huge flux ratio (10^7) between an Earth-like exoplanet in the socalled habitable zone and its host star makes it very difficult to direct image such systems. Nulling interferometry consists of a very powerful technique that combines destructively the light from two or more collectors to dim the starlight and to reveal faint companions in its vicinity. We have developed a new nulling experiment based on the fiber nuller principle. This fully symmetric reflective nulling bench aims at testing broadband nulling in both H and K bands as well as characterizing photonic fibers for modal filtering. We present in this paper the design, the development as well as preliminary results of the experiment.

Published
2010

15. Development of a statistical reduction method for the Palomar Fiber Nuller

Author

Danchi, William C., Delplancke, Françoise, Rajagopal, Jayadev K., Hanot, Charles, Mennesson, Bertrand, Serabyn, Eugene, Martin, Stefan, Liewer, Kurt, Loya, Frank, Mawet, Dimitri, Riaud, Pierre, Absil, Olivier, Danchi, William C., Delplancke, Françoise, Rajagopal, Jayadev K., Hanot, Charles, Mennesson, Bertrand, Serabyn, Eugene, Martin, Stefan, Liewer, Kurt, Loya, Frank, Mawet, Dimitri, Riaud, Pierre, and Absil, Olivier

Abstract

A unique statistical data analysis method has been developed for reducing nulling interferometry data. The idea is to make use of the statistical distributions of the fluctuating null depths and beam intensities to retrieve the astrophysical null depth in the presence of fluctuations. The approach yields an accuracy much better than is possible with standard data reduction methods, because the accuracy of the null depth is not limited by the sizes of the phase and intensity errors but by the uncertainties on their statistical distributions. The result is an improvement in the instrumental null depth measurement limit of roughly an order of magnitude. We show in this paper that broadband null depths of 10^(-4) can be measured in the lab with our infrared Fiber Nuller without achromatic phase shifters. On sky results are also dramatically improved, with measured contrasts up to a couple of 10^(-4) with our instrument mounted on the Hale telescope at the Palomar Observatory. This statistical analysis is not specific to our instrument and may be applicable to other interferometers.

Published
2010

16. Infrared Imaging

Author

Lawson, P. R., Traub, W. A., Unwin, S. C., Danchi, William, Lawson, Peter, Absil, Olivier, Hanot, Charles, Mawet, Dimitri, Lawson, P. R., Traub, W. A., Unwin, S. C., Danchi, William, Lawson, Peter, Absil, Olivier, Hanot, Charles, and Mawet, Dimitri

Abstract

A mid‐infrared mission would enable the detection of biosignatures of Earth‐like exoplanets around more than 150 nearby stars. The mid‐infrared spectral region is attractive for characterizing exoplanets because contrast with the parent star brightness is more favorable than in the visible (10 million vs. 10 billion), and because mid‐infrared light probes deep into a planet’s troposphere. Furthermore, the mid‐infrared offers access to several strong molecular features that are key signs of life, and also provides a measure of the effective temperature and size of a planet. Taken together, an infrared mission plus a visible one would provide a nearly full picture of a planet, including signs of life; with a measure of mass from an astrometric mission, we would have a virtually complete picture. A small infrared mission would have several telescopes that are rigidly connected, with a science return from the detection and characterization of super‐Earth sized to larger planets near the HZ, plus a direct measure of the exozodi brightness in the HZ. In a large infrared mission, with formation‐flying telescopes, planets from an Earth‐twin and upwards in mass could be detected and characterized, as well as the exozodi. If proceeded by an astrometric mission, the detection phase could be skipped and the mission devoted to characterization, as in the visible case; lacking an astrometric mission, an infrared one could proceed alone, as was discussed for a visible coronograph, and with similar caveats. The technology needed for a large formation‐flying mission is similar to that for a small connected‐element one (e.g., cryogenics and detectors), with the addition of formation-flying technology. The technology is now in hand to implement a probe‐scale mission; starlight suppression has even been demonstrated to meet the requirements of a flagship mission. However, additional development of formation‐flying technology is needed, particularly in‐space testing of sensors and guida

Published
2009

18. Taking the vector vortex coronagraph to the next level for ground- and space-based exoplanet imaging instruments: review of technology developments in the USA, Japan, and Europe

Author

Mawet, Dimitri, primary, Murakami, Naoshi, additional, Delacroix, Christian, additional, Serabyn, Eugene, additional, Absil, Olivier, additional, Baba, Naoshi, additional, Baudrand, Jacques, additional, Boccaletti, Anthony, additional, Burruss, Rick, additional, Chipman, Russell, additional, Forsberg, Pontus, additional, Habraken, Serge, additional, Hamaguchi, Shoki, additional, Hanot, Charles, additional, Ise, Akitoshi, additional, Karlsson, Mikael, additional, Kern, Brian, additional, Krist, John, additional, Kuhnert, Andreas, additional, Levine, Marie, additional, Liewer, Kurt, additional, McClain, Stephen, additional, McEldowney, Scott, additional, Mennesson, Bertrand, additional, Moody, Dwight, additional, Murakami, Hiroshi, additional, Niessner, Albert, additional, Nishikawa, Jun, additional, O'Brien, Nada, additional, Oka, Kazuhiko, additional, Park, Peggy, additional, Piron, Pierre, additional, Pueyo, Laurent, additional, Riaud, Pierre, additional, Sakamoto, Moritsugu, additional, Tamura, Motohide, additional, Trauger, John, additional, Shemo, David, additional, Surdej, Jean, additional, Tabirian, Nelson, additional, Traub, Wesley, additional, Wallace, James, additional, and Yokochi, Kaito, additional

Published
2011
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