المؤلفون: Garreau, Germain, Bigioli, Azzurra, Laugier, Romain, Raskin, Gert, Morren, Johan, Berger, Jean-Philippe, Dandumont, Colin, Goldsmith, Harry-Dean Kenchington, Gross, Simon, Ireland, Michael, Labadie, Lucas, Loicq, Jérôme, Madden, Stephen, Martin, Guillermo, Martinod, Marc-Antoine, Mazzoli, Alexandra, Sanny, Ahmed, Shao, Hancheng, Yan, Kunlun, Defrère, Denis

المصدر: J. Astron. Telesc. Instrum. Syst. 10(1), 015002 (2024)

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: Asgard/NOTT (previously Hi-5) is a European Research Council (ERC)-funded project hosted at KU Leuven and a new visitor instrument for the Very Large Telescope Interferometer (VLTI). Its primary goal is to image the snow line region around young stars using nulling interferometry in the L-band (3.5 to 4.0)$\mu$m, where the contrast between exoplanets and their host stars is advantageous. The breakthrough is the use of a photonic beam combiner, which only recently allowed the required theoretical raw contrast of $10^{-3}$ in this spectral range. Nulling interferometry observations of exoplanets also require a high degree of balancing between the four pupils of the VLTI in terms of intensity, phase, and polarization. The injection into the beam combiner and the requirements of nulling interferometry are driving the design of the warm optics and the injection system. The optical design up to the beam combiner is presented. It offers a technical solution to efficiently couple the light from the VLTI into the beam combiner. During the coupling, the objective is to limit throughput losses to 5% of the best expected efficiency for the injection. To achieve this, a list of different loss sources is considered with their respective impact on the injection efficiency. Solutions are also proposed to meet the requirements on beam balancing for intensity, phase, and polarization. The different properties of the design are listed, including the optics used, their alignment and tolerances, and their impact on the instrumental performances in terms of throughput and null depth. The performance evaluation gives an expected throughput loss of less than <6.4% of the best efficiency for the injection and a null depth of $\sim2.10^{-3}$, mainly from optical path delay errors outside the scope of this work.
Comment: Accepted for publication in JATIS. 23 pages, 11 figures, 8 tables

الوصول الحر: http://arxiv.org/abs/2402.09013Test

المؤلفون: Goldsmith, Harry-Dean Kenchington, Ireland, Michael J., Ma, Pan, Luther-Davies, Barry, Wang, Rongping, Noris, Barnaby, Tuthill, Peter, Madden, Stephen J.

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Astrophysics of Galaxies, Physics - Optics

الوصف: The future of exoplanet detection lies in the mid-infrared (MIR). The MIR region contains the blackbody peak of both hot and habitable zone exoplanets, making the contrast between starlight and planet light less extreme. It is also the region where prominent chemical signatures indicative of life exist, such as ozone at 9.7 microns. At a wavelength of 4 microns the difference in emission between an Earth-like planet and a star like our own is 80 dB. However a jovian planet, at the same separation exhibits 60 dB of contrast, or only 20 dB if it is hot due to its formation energy or being close to its host star. A two dimensional nulling interferometer, made with chalcogenide glass, has been measured to produce a null of 20 dB, limited by scattered light. Measures to increase the null depth to the theoretical limit of 60 dB are discussed.
Comment: Was published in SPIE: Optical and Infrared Interferometry and Imaging VI, Mike Ireland presented

الوصول الحر: http://arxiv.org/abs/1802.06727Test

المؤلفون: Goldsmith, Harry-Dean Kenchington, Cvetojevic, Nick, Ireland, Michael, Madden, Stephen

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics

الوصف: Understanding exoplanet formation and finding potentially habitable exoplanets is vital to an enhanced understanding of the universe. The use of nulling interferometry to strongly attenuate the central starlight provides the opportunity to see objects closer to the star than ever before. Given that exoplanets are usually warm, the 4 microns Mid-Infrared region is advantageous for such observations. The key performance parameters for a nulling interferometer are the extinction ratio it can attain and how well that is maintained across the operational bandwidth. Both parameters depend on the design and fabrication accuracy of the subcomponents and their wavelength dependence. Via detailed simulation it is shown in this paper that a planar chalcogenide photonic chip, consisting of three highly fabrication tolerant multimode interference couplers, can exceed an extinction ratio of 60 dB in double nulling operation and up to 40 dB for a single nulling operation across a wavelength window of 3.9 to 4.2 microns. This provides a beam combiner with sufficient performance, in theory, to image exoplanets.
Comment: Assigned issue as Vol. 23 No. 3 in Op. Express

الوصول الحر: http://arxiv.org/abs/1702.00468Test

المؤلفون: Goldsmith, Harry-Dean Kenchington, Cvetojevic, Nick, Ireland, Michael, Ma, Pan, Tuthill, Peter, Eggleton, Ben, Lawrence, John S., Debbarma, Sukanta, Luther-Davies, Barry, Madden, Stephen J.

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Physics - Optics

الوصف: Photonic integrated circuits are established as the technique of choice for a number of astronomical processing functions due to their compactness, high level of integration, low losses, and stability. Temperature control, mechanical vibration and acoustic noise become controllable for such a device enabling much more complex processing than can realistically be considered with bulk optics. To date the benefits have mainly been at wavelengths around 1550 nm but in the important Mid-Infrared region, standard photonic chips absorb light strongly. Chalcogenide glasses are well known for their transparency to beyond 10000 nm, and the first results from coupler devices intended for use in an interferometric nuller for exoplanetary observation in the Mid-Infrared L band (3800-4200 nm) are presented here showing that suitable performance can be obtained both theoretically and experimentally for the first fabricated devices operating at 4000 nm.
Comment: in Proc. SPIE 9907, Optical and Infrared Interferometry and Imaging V, 990730 (August 4, 2016)

الوصول الحر: http://arxiv.org/abs/1608.04438Test

المؤلفون: Goldsmith, Harry-Dean Kenchington, Huby, Elsa, Barjot, Kevin, Lallement, Manon, Rouan, Daniel, Martin, Guillermo, Vievard, Sebastien, Guyon, Olivier, Deo, Vincent, Pham, Cecil, Cassagnettes, Cedric, Billat, Adrien, Lacour, Sylvestre

المصدر: 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

الإتاحة: https://doi.org/10.1109/cleo/europe-eqec57999.2023.10232656Test
http://xplorestaging.ieee.org/ielx7/10231377/10231353/10232656.pdf?arnumber=10232656Test

المؤلفون: Garreau, Germain, Bigioli, Azzurra, Laugier, Romain, Raskin, Gert, Morren, Johan, Berger, Jean-Philippe, Dandumont, Colin, Goldsmith, Harry-Dean Kenchington, Gross, Simon, Ireland, Michael, Labadie, Lucas, Loicq, Jérôme, Madden, Stephen, Martin, Guillermo, Martinod, Marc-Antoine, Mazzoli, Alexandra, Sanny, Ahmed, Shao, Hancheng, Yan, Kunlun, Defrère, Denis

المصدر: Journal of Astronomical Telescopes, Instruments, and Systems; November 2023, Vol. 10 Issue: 1 p015002-015002, 1p