Ultra-Thin Large-Aperture Vacuum Windows for Millimeter Wavelengths Receivers
Denis Barkats, Marion I. Dierickx, John M. Kovac, Chris Pentacoff, P. A. R. Ade, Z. Ahmed, R. W. Aikin, K. D. Alexander, S. J. Benton, C. A. Bischof, J. J. Bock… 展开作者
Denis Barkats, Marion I. Dierickx, John M. Kovac, Chris Pentacoff, P. A. R. Ade, Z. Ahmed, R. W. Aikin, K. D. Alexander, S. J. Benton, C. A. Bischof, J. J. Bock, R. Bowens-Rubin, J. A. Brevik, I. Buder, E. Bullock, V. Buza, J. Connors, J. Cornelison, B. P. Crill, M. Crumrine, L. Duband, C. Dvorkin, J. P. Filippini, S. Fliescher, J. Grayson, G. Hall, M. Halpern, S. Harrison, S. R. Hildebrandt, G. C. Hilton, H. Hui, K. D. Irwin, J. Kang, K. S. Karkare, E. Karpel, J. P. Kaufman, B. G. Keating, S. Kefeli, S. A. Kernasovskiy, C. L. Kuo, K. Lau, N. A. Larsen, E. M. Leitch, M. Lueker, K. G. Megerian, L. Moncelsi, T. Namikawa, H. T. Nguyen, R. O'Brient, R. W. Ogburn, S. Palladino, C. Pryke, B. Racine, S. Richter, R. Schwarz, A. Schillaci, C. D. Sheehy, A. Soliman, T. St. Germaine, Z. K. Staniszewski, B. Steinbach, R. V. Sudiwala, G. P. Teply, K. L. Thompson, J. E. Tolan, C. Tucker, A. D. Turner, C. Umilta, A. G. Vieregg, A. Wandui, A. C. Weber, D. V. Wiebe, J. Willmert, C. L. Wong, W. L. K. Wu, H. Yang, K. W. Yoon, C. Zhang
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Published in Proc. SPIE. Presented at SPIE Astronomical Telescopes and Instrumentation Conference 10708: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, June 2018. 14 pages, 7 figures
Targeting faint polarization patterns arising from Primordial Gravitational Waves in the Cosmic Microwave Background requires excellent observational sensitivity. Optical elements in small aperture experiments such as Bicep3 and Keck Array are designed to optimize throughput and minimize losses from transmission, reflection and scattering at millimeter wavelengths. As aperture size increases, cryostat vacuum windows must withstand larger forces from atmospheric pressure and the solution has often led to a thicker window at the expense of larger transmission loss. We have identified a new candidate material for the fabrication of vacuum windows: with a tensile strength two orders of magnitude larger than previously used materials, woven high-modulus polyethylene could allow for dramatically thinner windows, and therefore significantly reduced losses and higher sensitivity. In these proceedings we investigate the suitability of high-modulus polyethylene windows for ground-based CMB experiments, such as current and future receivers in the Bicep/Keck Array program. This includes characterizing their optical transmission as well as their mechanical behavior under atmospheric pressure. We find that such ultra-thin materials are promising candidates to improve the performance of large-aperture instruments at millimeter wavelengths, and outline a plan for further tests ahead of a possible upcoming field deployment of such a science-grade window.
We present a concept of a millimeter wavefront sensor that allows real-time sensing of the surface of a ground-based millimeter/submillimeter telescope. It is becoming important for ground-based millimeter/submillimeter astronomy to make telescopes larger with keeping their surface accurate. To establish `millimetric adaptive optics (MAO)' that instantaneously corrects the wavefront degradation induced by deformation of telescope optics, our wavefront sensor based on radio interferometry measures changes in excess path lengths from characteristic positions on the primary mirror surface to the …
New experiments that target the B-mode polarization signals in the Cosmic Microwave Background require more sensitivity, more detectors, and thus larger-aperture millimeter-wavelength telescopes, than previous experiments. These larger apertures require ever larger vacuum windows to house cryogenic optics. Scaling up conventional vacuum windows, such as those made of High Density Polyethylene (HDPE), require a corresponding increase in the thickness of the window material to handle the extra force from the atmospheric pressure. Thicker windows cause more transmission loss at ambient temperatur…
The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers the 35-50 GHz frequency band. Development of prototype receivers, including the key components and subsystems has been completed and two sets of prototype receivers were fully tested. We will provide an overview of the ALMA Band 1 science goals, and its requirements and design for use on the ALMA. The receiver development status will also be discussed and the infrastructure, integration, evaluation of fully-assembled band 1 receiver system will be covered. Finally, a discussion of the technical and management challen…
The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) survey experiment that consists of three 0.5 m small-aperture telescopes (SATs) and one 6 m large-aperture telescope (LAT), sited at an elevation of 5200 m in the Atacama Desert in Chile. In order to meet the sensitivity requirements set for next-generation CMB telescopes, the LAT will deploy 30,000 transition edge sensor (TES) detectors at 100 mK across 7 optics tubes (OT), all within the Large Aperture Telescope Receiver (LATR). Additionally, the LATR has the capability to expand to 62,000 TES across 13 OTs. The …
A Wideband Millimeter-wave Receiver at 210-350 GHz for LMT-FINER
National Astronomical Observatory of Japan（日本国立天文台）；The University of Electro-Communications（电气通信大学）；Nagoya University（名古屋大学）；Kitami Institute of Technology（北见工业大学）；Suwa University of Science（诹访科学大学）；National Institute of Information and Communications Technology（信息通信研究机构）；The Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）
We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300K and 2) the beam pattern expected from the rece…
FINER: development of the wideband millimeter-wave receiver system and preparations for first light on the Large Millimeter Telescope
Kitami Institute of Technology（北见工业大学）；Nagoya University（名古屋大学）；The University of Electro-Communications（电气通信大学）；University of Tsukuba（筑波大学）；Waseda University（早稻田大学）；National Astronomical Observatory of Japan（日本国立天文台）；The Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）；The University of Tokyo（东京大学）；Suwa University of Science（諏訪精密工科大学）；Keio University（庆应义塾大学）；National Institute of Information and Communications Technology（信息通信研究机构）；Chalmers University of Technology（查尔姆斯理工大学）；Chiba University（千叶大学）；Hokkaido University（北海道大学）；Instituto Nacional de Astrofísica, Óptica y Electrónica（墨西哥国家天体物理学、光学和电子研究所）；University of Yamanashi（山梨大学）；Osaka Metropolitan University（大阪公立大学）；Japan Aerospace Exploration Agency（日本宇宙航空研究开发机构）
The Simons Observatory (SO) Large Aperture Telescope Receiver (LATR) will be coupled to the Large Aperture Telescope located at an elevation of 5,200 m on Cerro Toco in Chile. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date with a diameter of 2.4 m and a length of 2.6 m. It cools 1200 kg of material to 4 K and 200 kg to 100 mk, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultim…
The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) using a series of telescopes which will cover angular scales between one arcminute and tens of degrees, contain over 60,000 detectors, and sample frequencies between 27 and 270 GHz. SO will consist of a six-meter-aperture telescope coupled to over 30,000 detectors along with an array of half-meter aperture refractive cameras, which together couple to an additional 30,000+ detectors. SO will measure fundamental cosmological parameters of our universe, find high reds…
Development Status of Wideband Millimeter-Wave Receivers for LMT-FINER
National Astronomical Observatory of Japan（日本国立天文台）；University of Electro-Communications（电气通信大学）；Nagoya University（名古屋大学）；Kitami Institute of Technology（北见工业大学）
The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) using a series of telescopes which will cover angular scales between one arcminute and tens of degrees and sample frequencies between 27 and 270 GHz. Here we present the current design of the large aperture telescope receiver (LATR), a 2.4 m diameter cryostat that will be mounted on the SO 6 m telescope and will be the largest CMB receiver to date. The cryostat size was chosen to take advantage of the large focal plane area having high Strehl ratios, which is inher…
Radio absorptive materials (RAMs) are key elements for receivers in the millimeter-wave range. For astronomical applications, cryogenic receivers are widely used to achieve a high-sensitivity. These cryogenic receivers, in particular the receivers for the cosmic microwave background, require that the RAM has low surface reflectance ($\lesssim 1\%$) in a wide frequency range (20--300 GHz) to minimize the undesired stray light to detectors. We develop a RAM that satisfies this requirement based on a production technology using a 3D-printed mold (named as RAM-3pm). This method allows us to shape …
Data rates in an interstellar communication network suffer from the inverse square law due to the vast distances between the stars. To achieve high (Gbits/s) data rates, some combination of large apertures and high power is required. Alternatively, signals can be focused by the gravitational lenses of stars to yield gains of order $10^{9}$, compared to the direct path. Gravitational lens physics imposes a set of constraints on the sizes and locations of receivers and apertures. These characteristics include the minimum and maximum receiver size, the maximum transmitter size, and the heliocentr…
We report the results of the performance characterization of a prototype wavefront sensor for millimetric adaptive optics (MAO) installed on the Nobeyama 45 m radio telescope. MAO is a key component to realize a future large-aperture submillimeter telescope, such as Large Submillimeter Telescope (LST) or Atacama Large Aperture Submillimeter Telescope (AtLAST). The difficulty of MAO is, however, real-time sensing of wavefront deformation with ~10 um accuracy across the aperture. Our wavefront sensor operating at 20 GHz measures the radio path length between a certain position of the primary mir…
The Simons Observatory (SO) will observe the cosmic microwave background (CMB) from Cerro Toco in the Atacama Desert of Chile. The observatory consists of three 0.5 m Small Aperture Telescopes (SATs) and one 6 m Large Aperture Telescope (LAT), covering six frequency bands centering around 30, 40, 90, 150, 230, and 280 GHz. The SO observations will transform the understanding of our universe by characterizing the properties of the early universe, measuring the number of relativistic species and the mass of neutrinos, improving our understanding of galaxy evolution, and constraining the properti…
Antenna efficiency is one of the most important figures-of-merit of a radio telescope for observations especially at millimeter wavelengths or shorter wavelengths, even for a multibeam radio telescope. To analyze a system with a beam waveguide, a lossless antenna consisting of two apertures in series is considered in the frame of the scalar wave approximation. We found that the antenna efficiency can be evaluated with the field distribution over the second aperture, and that the antenna efficiency is factorized into three factors: efficiencies of beam coupling, transmission spillover, and rece…
The Five-hundred-meter Aperture Spherical radio Telescope (FAST) passed national acceptance and is taking pilot cycle of 'Shared-Risk' observations. The 19-beam receiver covering 1.05-1.45 GHz was used for most of these observations. The electronics gain fluctuation of the system is better than 1\% over 3.5 hours, enabling enough stability for observations. Pointing accuracy, aperture efficiency and system temperature are three key parameters of FAST. The measured standard deviation of pointing accuracy is 7.9$''$, which satisfies the initial design of FAST. When zenith angle is less than 26.4…
The Atacama Millimeter/submillimeter Array (ALMA) Phasing Project (APP) has developed and deployed the hardware and software necessary to coherently sum the signals of individual ALMA antennas and record the aggregate sum in Very Long Baseline Interferometry (VLBI) Data Exchange Format. These beamforming capabilities allow the ALMA array to collectively function as the equivalent of a single large aperture and participate in global VLBI arrays. The inclusion of phased ALMA in current VLBI networks operating at (sub)millimeter wavelengths provides an order of magnitude improvement in sensitivit…
CMB-S4 -- the next-generation ground-based cosmic microwave background (CMB) experiment - will significantly advance the sensitivity of CMB measurements and improve our understanding of the origin and evolution of the universe. CMB-S4 will deploy large-aperture telescopes fielding hundreds of thousands of detectors at millimeter wavelengths. We present the baseline optical design concept of the large-aperture CMB-S4 telescopes, which consists of two optical configurations: (i) a new off-axis, three-mirror, free-form anastigmatic design and (ii) the existing coma-corrected crossed-Dragone desig…
The corrugated horn is a high performance feed often used in radio telescopes. There has been a growing demand for wideband optics and corrugated horns in millimeter and submillimeter-wave receivers. It improves the observation efficiency and allows us to observe important emission lines such as CO in multiple excited states simultaneously. However, in the millimeter/submillimeter band, it has been challenging to create a conical corrugated horn with a fractional bandwidth of ~60% because the wavelength is very short, making it difficult to make narrow corrugations. In this study, we designed …
