publications
publications by categories in reversed chronological order.
major contribution
2020
- SPIEPor, Emiel H., Soummer, Rémi, Noss, James, and St. Laurent, KathrynProc. SPIE 11443 (2020)
Modern coronagraph design relies on advanced, large-scale optimization processes that require an ever increasing amount of computational resources. In this paper, we restrict ourselves to the design of Apodized Pupil Lyot Coronagraphs (APLCs). To produce APLC designs for future giant space telescopes, we require a fine sampling for the apodizer to resolve all small features, such as segment gaps, in the telescope pupil. Additionally, we require the coronagraph to operate in broadband light and be insensitive to small misalignments of the Lyot stop. For future designs we want to include passive suppression of low-order aberrations and finite stellar diameters. The memory requirements for such an optimization would exceed multiple terabytes for the problem matrix alone.
We therefore want to reduce the number of variables and constraints to minimize the size of the problem matrix. We show how symmetries in the pupil and Lyot stop are expressed in the complete optimization problem, and allow removal of both variables and constraints. Each mirror symmetry reduces the problem size by a factor of four. Secondly, we introduce progressive refinement, which uses low-resolution optimizations as a prior for higher resolutions. This lets us remove the majority of variables from the high-resolution optimization. Together these two improvements require up to 256x less computer memory, with a corresponding speed increase. This allows for greater exploration of the phase space of the focal-plane mask and Lyot-stop geometry, and easier simulation of sensitivity to Lyot-stop misalignments. Moreover, apodizers can now be optimized at their native manufactured resolution.
- A&AHaffert, S.Y., Por, E.H., Keller, C.U., Kenworthy, M.A., Doelman, D.S., Snik, F., and Escuti, M.J.A&A 635, A56 (2020)
We present the monochromatic lab verification of the newly developed SCAR coronagraph that combines a phase plate (PP) in the pupil with a microlens-fed single-mode fiber array in the focal plane. The two SCAR designs that have been measured, create respectively a 360 degree and 180 degree dark region from 0.8-2.4λ/D around the star. The 360 SCAR has been designed for a clear aperture and the 180 SCAR has been designed for a realistic aperture with central obscuration and spiders. The 360 SCAR creates a measured stellar null of 2-3 × 10-4, and the 180 SCAR reaches a null of 1 × 10-4. Their monochromatic contrast is maintained within a range of ±0.16λ/D peak-to-valley tip-tilt, which shows the robustness against tip-tilt errors. The small inner working angle and tip-tilt stability makes the SCAR coronagraph a very promising technique for an upgrade of current high-contrast instruments to characterize and detect exoplanets in the solar neighborhood.
- A&APor, E.H., and Haffert, S.Y.A&A 635, A55 (2020)
Context: The recent discovery of an Earth-mass exoplanet around the nearby star Proxima Centauri provides a prime target for the search for life on planets outside our solar system. Atmospheric characterization of these planets has been proposed by blocking the starlight with a stellar coronagraph and using a high-resolution spectrograph to search for reflected starlight off the planet.
Aims: Due to the large flux ratio and small angular separation between Proxima b and its host star (≲10-7 and ≲2.2λ/D respectively; at 750 nm for an 8 m-class telescope) the coronagraph requires high starlight suppression at extremely-low inner working angles. Additionally, it must operate over a broad spectral bandwidth and under residual telescope vibrations. This allows for efficient use of spectroscopic post-processing techniques. We aim to find the global optimum of an integrated coronagraphic integral-field spectrograph.
Methods: We present the Single-mode Complex Amplitude Refinement (SCAR) coronagraph that uses a microlens-fed single-mode fiber array in the focal plane downstream from a pupil-plane phase plate. The mode-filtering property of the single-mode fibers allows for the nulling of starlight on the fibers. The phase pattern in the pupil plane is specifically designed to take advantage of this mode-filtering capability. Second-order nulling on the fibers expands the spectral bandwidth and decreases the tip-tilt sensitivity of the coronagraph.
Results: The SCAR coronagraph has a low inner working angle (∼1λ/D) at a contrast of < 3 × 10-5 for the six fibers surrounding the star using a sufficiently-good adaptive optics system. It can operate over broad spectral bandwidths (∼20%) and delivers high throughput (> 50% including fiber injection losses). Additionally, it is robust against tip-tilt errors (∼0.1λ/D rms). We present SCAR designs for both an unobstructed and a VLT-like pupil.
Conclusions: The SCAR coronagraph is a promising candidate for exoplanet detection and characterization around nearby stars using current high-resolution imaging instruments.
- ApJPor, Emiel H.ApJ 888, 127 (2020)
The phase-apodized-pupil Lyot coronagraph (PAPLC) is a pairing of the apodized-pupil Lyot coronagraph and the apodizing phase plate (APP) coronagraph. We describe a numerical optimization method to obtain globally optimal solutions for the phase apodizers for arbitrary telescope pupils, based on the linear map between complex-amplitude transmission of the apodizer and the electric field in the post-coronagraphic focal plane. PAPLCs with annular focal-plane masks and point-symmetric dark zones perform analogous to their corresponding APLCs. However, with a knife-edge focal-plane mask and one-sided dark zones, the PAPLC yields inner working angles as close as 1.4λ/D at contrasts of 10−10 and a maximum post-coronagraphic throughput of >75% for telescope apertures with central obscurations of up to 30%. We present knife-edge PAPLC designs optimized for the VLT/SPHERE instrument and the LUVOIR-A aperture. These designs show that the knife-edge PAPLC retains its performance, even for realistic telescope pupils with struts, segments, and non-circular outer edges.
2018
- A&ACantalloube, F., Por, E.H., Dohlen, K., Sauvage, J. -F., Vigan, A., Kasper, M., Bharmal, N., Henning, T., Brandner, W., Milli, J., Correia, C., and Fusco, T.A&A 620, L10 (2018)
The latest generation of high-contrast instruments dedicated to exoplanets and circumstellar disk imaging are equipped with extreme adaptive optics and coronagraphs to reach contrasts of up to 10-4 at a few tenths of arcseconds in the near-infrared. The resulting image shows faint features, only revealed with this combination, such as the wind driven halo. The wind driven halo is due to the lag between the adaptive optics correction and the turbulence speed over the telescope pupil. However, we observe an asymmetry of this wind driven halo that was not expected when the instrument was designed. In this letter, we describe and demonstrate the physical origin of this asymmetry and support our explanation by simulating the asymmetry with an end-to-end approach. From this work, we find that the observed asymmetry is explained by the interference between the AO-lag error and scintillation effects, mainly originating from the fast jet stream layer located at about 12 km in altitude. Now identified and interpreted, this effect can be taken into account for further design of high-contrast imaging simulators, next generation or upgrade of high-contrast instruments, predictive control algorithms for adaptive optics, or image post-processing techniques.
- SPIEPor, Emiel H., Haffert, Sebastiaan Y., Radhakrishnan, Vikram M., Doelman, David S., van Kooten, Maaike, and Bos, Steven P.Proc. SPIE 10703 (2018)
HCIPy is a package written in Python for simulating the interplay between wavefront control and coronagraphic systems. By defining an element which merges values/coefficients with its sampling grid/modal basis into a single object called Field, this minimizes errors in writing the code and makes it clearer to read. HCIPy provides a monochromatic Wavefront and defines a Propagator that acts as the transformation between two wavefronts. In this way a Propagator acts as any physical part of the optical system, be it a piece of free space, a thin complex apodizer or a microlens array. HCIPy contains Fraunhofer and Fresnel propagators through free space. It includes an implementation of a thin complex apodizer, which can modify the phase and/or amplitude of a wavefront, and forms the basis for more complicated optical elements. Included in HCIPy are wavefront errors (modal, power spectra), complex apertures (VLT, Keck or Subaru pupil), coronagraphs (Lyot, vortex or apodizing phase plate coronagraph), deformable mirrors, wavefront sensors (Shack-Hartmann, Pyramid, Zernike or phase-diversity wavefront sensor) and multi-layer atmospheric models including scintillation). HCIPy aims to provide an easy-to-use, modular framework for wavefront control and coronagraphy on current and future telescopes, enabling rapid prototyping of the full high-contrast imaging system. Adaptive optics and coronagraphic systems can be easily extended to include more realistic physics. The package includes a complete documentation of all classes and functions, and is available as open-source software.
2017
- SPIEPor, Emiel H.Proc. SPIE 10400 (2017)
Direct observations of exoplanets require a stellar coronagraph to suppress the diffracted starlight. An Apodizing Phase Plate (APP) coronagraph consists of a carefully designed phase-only mask in the pupil plane of the telescope. This mask alters the point spread function in such a way that it contains a dark zone at some off-axis region of interest, while still retaining a high Strehl ratio (and therefore high planet throughput). Although many methods for designing such a phase mask exist, none of them provide a guarantee of global optimality. Here we present a method based on generalization of the phase-only mask to a complex amplitude mask. Maximizing the Strehl ratio while simultaneously constraining the stellar intensity in the dark zone turns out to be a quadratically constrained linear algorithm, for which a global optimum can be found using large-scale numerical optimizers. This generalized problem yields phase-only solutions. These solutions are therefore also solutions of the original problem. Using this optimizer we perform parameter studies on the inner and outer working angle, the contrast and the size of the secondary obscuration of the telescope aperture for both one-sided and annular dark zones. We reach Strehl ratios of > 65% for a 10-5 contrast from 1.8 to 10λ/D with a one-sided dark zone for a VLT-like secondary obscuration. This study provides guidelines for designing APPs for more realistic apertures.
2016
- SPIEPor, Emiel H., and Keller, Christoph U.Proc. SPIE 9909 (2016)
The direct detection and spectral characterization of exoplanets requires a coronagraph to suppress the diffracted star light. Amplitude and phase aberrations in the optical train fill the dark zone of the coronagraph with quasistatic speckles that limit the achievable contrast. Focal-plane electric field sensing, such as phase diversity introduced by a deformable mirror (DM), is a powerful tool to minimize this residual star light. The residual electric field can be estimated by sequentially applying phase probes on the DM to inject star light with a well-known amplitude and phase into the dark zone and anazlying the resulting intensity images. The DM can then be used to add light with the same amplitude but opposite phase to destructively interfere with this residual star light.
Using a static phase-only pupil-plane element we create holographic copies of the point spread function (PSF), each superimposed with a certain pupil-plane phase probe. We therefore obtain all intensity images simultaneously while still retaining a central, unaltered science PSF. The electric field sensing method only makes use of the holographic copies, allowing for correction of the residual electric field while retaining the central PSF for uninterrupted science data collection. In this paper we demonstrate the feasibility of this method with numerical simulations.
minor contribution
2020
- SPIEEstimating low-order aberrations through a Lyot coronagraph with a Zernike wavefront sensor for exoplanet imagingPourcelot, Raphaël, N’Diaye, Mamadou, Brady, Greg, Carbillet, Marcel, Dohlen, Kjetil, Fowler, Julia, Laginja, Iva, Maclay, Matthew, Noss, James, Perrin, Marshall, Petrone, Pete, Por, Emiel, Sauvage, Jean-François, Soummer, Rémi, Vigan, Arthur, and Will, ScottarXiv e-prints, arXiv:2012.08423 (2020)
- SPIEHigh contrast imaging for the enhanced resolution imager and spectrometer (ERIS)Kenworthy, Matthew A., Snik, Frans, Keller, Christoph U., Doelman, David, Por, Emiel H., Absil, Olivier, Carlomagno, Brunella, Karlsson, Mikael, Huby, Elsa, Glauser, Adrian M., Quanz, Sascha P., and Taylor, William D.arXiv e-prints, arXiv:2012.01963 (2020)
- ApOptSnik, Frans, Bos, Steven P., Brackenhoff, Stefanie A., Doelman, David S., Por, Emiel H., Bettonvil, Felix, Rodenhuis, Michiel, Vorobiev, Dmitry, Eshelman, Laura M., and Shaw, Joseph A.Applied Optics 59, F71 (2020)
- A&ACantalloube, F., Farley, O.J.D., Milli, J., Bharmal, N., Brandner, W., Correia, C., Dohlen, K., Henning, Th., Osborn, J., Por, E., Suárez Valles, M., and Vigan, A.A&A 638, A98 (2020)
- PASPDoelman, David S., Por, Emiel H., Ruane, Garreth, Escuti, Michael J., and Snik, FransPASP 132, 045002 (2020)
- ESOSPHERE+: Imaging young Jupiters down to the snowlineBoccaletti, A., Chauvin, G., Mouillet, D., Absil, O., Allard, F., Antoniucci, S., Augereau, J. -C., Barge, P., Baruffolo, A., Baudino, J. -L., Baudoz, P., Beaulieu, M., Benisty, M., Beuzit, J. -L., Bianco, A., Biller, B., Bonavita, B., Bonnefoy, M., Bos, S., Bouret, J. -C., Brandner, W., Buchschache, N., Carry, B., Cantalloube, F., Cascone, E., Carlotti, A., Charnay, B., Chiavassa, A., Choquet, E., Clenet, Y., Crida, A., De Boer, J., De Caprio, V., Desidera, S., Desert, J. -M., Delisle, J. -B., Delorme, P., Dohlen, K., Doelman, D., Dominik, C., Orazi, V. D, Dougados, C., Doute, S., Fedele, D., Feldt, M., Ferreira, F., Fontanive, C., Fusco, T., Galicher, R., Garufi, A., Gendron, E., Ghedina, A., Ginski, C., Gonzalez, J. -F., Gratadour, D., Gratton, R., Guillot, T., Haffert, S., Hagelberg, J., Henning, T., Huby, E., Janson, M., Kamp, I., Keller, C., Kenworthy, M., Kervella, P., Kral, Q., Kuhn, J., Lagadec, E., Laibe, G., Langlois, M., Lagrange, A. -M., Launhardt, R., Leboulleux, L., Le Coroller, H., Li Causi, G., Loupias, M., Maire, A.L., Marleau, G., Martinache, F., Martinez, P., Mary, D., Mattioli, M., Mazoyer, J., Meheut, H., Menard, F., Mesa, D., Meunier, N., Miguel, Y., Milli, J., Min, M., Molliere, P., Mordasini, C., Moretto, G., Mugnier, L., Muro Arena, G., Nardetto, N., Diaye, M. N, Nesvadba, N., Pedichini, F., Pinilla, P., Por, E., Potier, A., Quanz, S., Rameau, J., Roelfsema, R., Rouan, D., Rigliaco, E., Salasnich, B., Samland, M., Sauvage, J. -F., Schmid, H. -M., Segransan, D., Snellen, I., Snik, F., Soulez, F., Stadler, E., Stam, D., Tallon, M., Thebault, P., Thiebaut, E., Tschudi, C., Udry, S., van Holstein, R., Vernazza, P., Vidal, F., Vigan, A., Waters, R., Wildi, F., Willson, M., Zanutta, A., Zavagno, A., and Zurlo, A.arXiv e-prints, arXiv:2003.05714 (2020)
- AASCoronagraphy for segmented apertures: Results from demonstrations on the HICAT testbedPerrin, M., Brady, G., Comeau, T., Fowler, J., Gontrum, R., Hagopian, J., Kautz, M., Kurtz, H., Laginja, I., McChesney, E., Noss, J., Petrone, P., Por, E., Pueyo, L., Sauvage, J., Scott, N., Shiri, R., Sivaramakrishnan, A., Subedi, H., Valenzuela, A., Weinstock, S., Will, S., Zhang, R., and Soummer, R.American Astronomical Society Meeting Abstracts 235, 280.08 (2020)
2019
- OExprHaffert, S.Y., Por, E.H., and Keller, C.U.Optics Express 27, 33925 (2019)
- AO4ELTHigh contrast imaging with ELT/METIS: The wind driven halo, from SPHERE to METISCantalloube, Faustine, Absil, Olivier, Bertram, Thomas, Brandner, Wolfgang, Delacroix, Christian, Feldt, Markus, Kenworthy, Matthew, Kulas, Martin, Milli, Julien, Neureuther, Philip, Orban de Xivry, Gilles, Pathak, Prashant, Por, Emiel, Scheithauer, Silvia, Steuer, Horst, and van Boekel, RoyAO4ELT6 (2019)
- JATISMiller, Kelsey, Males, Jared R., Guyon, Olivier, Close, Laird M., Doelman, David, Snik, Frans, Por, Emiel, Wilby, Michael J., Keller, Christoph, Bohlman, Chris, Van Gorkom, Kyle, Rodack, Alexander, Knight, Justin, Lumbres, Jennifer, Bos, Steven, and Jovanovic, NemanjaJATIS 5, 049004 (2019)
- SPIELaginja, Iva, Leboulleux, Lucie, Pueyo, Laurent, Soummer, Rémi, Sauvage, Jean-François, Mugnier, Laurent, Coyle, Laura E., Knight, J. Scott, St. Laurent, Kathryn, Por, Emiel H., and Noss, JamesProc. SPIE 11117, 1111717 (2019)
- BAASStatus of Space-based Segmented-Aperture Coronagraphs for Characterizing Exo-Earths Around Sun-Like StarsShaklan, Stuart, Crill, Brendan, Belikov, Ruslan, Bryson, Stephen, Bendek, Eduardo, Bolcar, Matt, Fogarty, Kevin, Krist, John, Mawet, Dimitri, Mejia Prada, Camilo, Mazoyer, Johan, N’Diaye, Mamadou, Noss, James, Juanola-Parramon, Roser, Por, Emiel, Riggs, A.J. Eldorado, Ruane, Garreth, Siegler, Nicholas, Sirbu, Dan, Sivaramakrishnan, Anand, Soummer, Rémi, St. Laurent, Kathryn, Stark, Christopher, and Zimmerman, NeilBAAS (2019)
2018
- SPIERuane, G., Riggs, A., Mazoyer, J., Por, E.H., N’Diaye, M., Huby, E., Baudoz, P., Galicher, R., Douglas, E., Knight, J., Carlomagno, B., Fogarty, K., Pueyo, L., Zimmerman, N., Absil, O., Beaulieu, M., Cady, E., Carlotti, A., Doelman, D., Guyon, O., Haffert, S., Jewell, J., Jovanovic, N., Keller, C., Kenworthy, M.A., Kuhn, J., Miller, K., Sirbu, D., Snik, F., Wallace, J. Kent, Wilby, M., and Ygouf, M.Proc. SPIE 10698, 106982S (2018)
- SPIEBaruffolo, Andrea, Salasnich, Bernardo, Puglisi, Alfio, Grani, Paolo, Gao, Xiaofeng, Wiezorrek, Erich, Fantinel, Daniela, Di Rico, Gianluca, Knudstrup, Jens, Moins, Christophe, Absil, Olivier, Barr, David, Buron, Alexander, Huby, Elsa, Kenworthy, Matthew, Kiekebusch, Mario, Popovic, Dan, Por, Emiel, Rau, Christian, Soenke, Christian, and Waring, ChrisProc. SPIE 10707, 107071H (2018)
- SPIEBos, Steven P., Doelman, David S., de Boer, Jos, Por, Emiel H., Norris, Barnaby, Escuti, Michael J., and Snik, FransProc. SPIE 10706, 107065M (2018)
- SPIESnik, Frans, Absil, Olivier, Baudoz, Pierre, Beaulieu, Mathilde, Bendek, Eduardo, Cady, Eric, Carlomagno, Brunella, Carlotti, Alexis, Cvetojevic, Nick, Doelman, David, Fogarty, Kevin, Galicher, Raphaël., Guyon, Olivier, Haffert, Sebastiaan, Huby, Elsa, Jewell, Jeffrey, Jovanovic, Nemanja, Keller, Christoph, Kenworthy, Matthew A., Knight, Justin, Kuhn, Jonas, Mazoyer, Johan, Miller, Kelsey, N’Diaye, Mamadou, Norris, Barnaby, Por, Emiel, Pueyo, Laurent, Riggs, A.J. Eldorado, Ruane, Garreth, Sirbu, Dan, Wallace, J. Kent, Wilby, Michael, and Ygouf, MarieProc. SPIE 10706, 107062L (2018)
- SPIELumbres, Jennifer, Males, Jared, Douglas, Ewan, Close, Laird, Guyon, Olivier, Cahoy, Kerri, Carlton, Ashley, Clark, Jim, Doelman, David, Feinberg, Lee, Knight, Justin, Marlow, Weston, Miller, Kelsey, Morzinski, Katie, Por, Emiel, Rodack, Alexander, Schatz, Lauren, Snik, Frans, Van Gorkom, Kyle, and Wilby, MichaelProc. SPIE 10703, 107034Z (2018)
- SPIEHaffert, S.Y., Wilby, M.J., Keller, C.U., Snellen, I.A.G., Doelman, D.S., Por, E.H., van Kooten, M., Bos, S.P., and Wardenier, J.Proc. SPIE 10703, 1070323 (2018)
- SPIEJovanovic, Nemanja, Absil, Olivier, Baudoz, Pierre, Beaulieu, Mathilde, Bottom, Michael, Cady, Eric, Carlomagno, Brunella, Carlotti, Alexis, Doelman, David, Fogarty, Kevin, Galicher, Raphaël., Guyon, Olivier, Haffert, Sebastiaan, Huby, Elsa, Jewell, Jeffrey, Keller, Christoph, Kenworthy, Matthew A., Knight, Justin, Kühn, Jonas, Miller, Kelsey, Mazoyer, Johan, N’Diaye, Mamadou, Por, Emiel, Pueyo, Laurent, Riggs, A.J.E., Ruane, Garreth, Sirbu, Dan, Snik, Frans, Wallace, J.K., Wilby, Michael, and Ygouf, MarieProc. SPIE 10703, 107031U (2018)
- SPIEMiller, Kelsey, Males, Jared R., Guyon, Olivier, Close, Laird M., Doelman, David, Snik, Frans, Por, Emiel, Wilby, Michael J., Bohlman, Chris, Lumbres, Jennifer, Van Gorkom, Kyle, Kautz, Maggie, Rodack, Alexander, Knight, Justin, Jovanovic, Nemanja, Morzinski, Katie, and Schatz, LaurenProc. SPIE 10703, 107031T (2018)
- SPIEKenworthy, Matthew A., Absil, Olivier, Carlomagno, Brunella, Agócs, Tibor, Por, Emiel H., Bos, Steven, Brandl, Bernhard, and Snik, FransProc. SPIE 10702, 10702A3 (2018)
- SPIEKenworthy, Matthew A., Snik, Frans, Keller, Christoph U., Doelman, David, Por, Emiel H., Absil, Olivier, Carlomagno, Brunella, Karlsson, Mikael, Huby, Elsa, Glauser, Adrian M., Quanz, Sascha P., and Taylor, William D.Proc. SPIE 10702, 1070246 (2018)
- SPIEDoelman, D.S., Tuthill, P., Norris, B., Wilby, M.J., Por, E.H., Keller, C.U., Escuti, M.J., and Snik, F.Proc. SPIE 10701, 107010T (2018)