Interferometry and Aperture Synthesis
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Interferometric Spectrometers
LBNL-40663 UC-410 . ERNEST ORLANDO LAWRENCE BERKELEY NATIONAL LABORATORY Interferometric Spectrometers Anne Thome and Malcolm Howells Accelerator and Fusion Research Division June 1997 To be published as a chapter in Techniques ofVacuum Ultraviolet Physics, J~A-. Samson and D A. Ederer, eds.-, ·..-:~-:.:-':.::;:::;;;;r,;-:·.::~:~~:.::~-~~'*-~~,~~~;.=;t,ffl;.H;~:;;$,'~.~:~~::;;.:~< :.:,:::·.;:~·:..~.,·,;;;~.· l.t..•.-J.' "'"-""···,:·.:·· \ '-· . _ .....::' .~..... .:"~·~-!r.r;.e,.,...;. 17"'JC.(.; .• ,'~..: .••, ..._i;.·;~~(.:j. ... ..,.~1\;i:;.~ ...... J:' Academic Press, ....... ·.. ·... :.: ·..... ~ · ··: ·... · . .. .. .. - • 0 • ···...::; •• 0 ·.. • •• • •• ••• , •• •• •• ••• •••••• , 0 •• 0 .............. -·- " DISCLAIMER. This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain cmTect information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legahesponsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the -
Radio Astronomy & Radio Telescopes
Radio Astronomy & Radio Telescopes Tasso Tzioumis ([email protected]) Australia Telescope National Facility (ATNF) sms2020, Stellenbosch 2-6 March 2020 CSIRO ASTRONOMY AND SPACE SCIENCE Radio Astronomy – ITU definition 1.13 radio astronomy: Astronomy based on the reception of radio waves of cosmic origin. 1.5 radio waves or hertzian waves: Electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide. • Astronomy covers the whole electromagnetic spectrum • Radio astronomy is the “low energy” part of the spectrum é 3 000 GHz Radioastronomy & Radio telescopes | Tasso Tzioumis Radio Astronomy “special” characteristics Technical challenges • Very faint signals – measured in 10-26 W/m2/Hz (-260 dBW) • “Power collected by all radiotelescopes since the start of radio astronomy would light a 1W bulb for less than 1 second” • à Need “sensitivity” i.e. large antennas and/or arrays of many antennas • à Very susceptible to intereference • Celestial structures at all scales: from very large to very small • à Need “spatial resolution” i.e. ability to see the details at all scales • à Need large antennas and/or arrays of many antennas • Astronomical events at all timescales(from < 1ms to > millions years) & and at all spectral resolutions (from < 1 Hz to GHz) • à Need very high time and frequency resolution • à Sensitive telescopes and arrays & extreme technical challenges Radioastronomy & Radio telescopes | Tasso Tzioumis Radio Astronomy “special” characteristics Scientific challenges • Radio -
A Precise and Accurate Determination of the Cosmic Microwave Background Temperature at Z =0.89
A&A 551, A109 (2013) Astronomy DOI: 10.1051/0004-6361/201220613 & c ESO 2013 Astrophysics A precise and accurate determination of the cosmic microwave background temperature at z =0.89 S. Muller1, A. Beelen2,J.H.Black1,S.J.Curran3,4, C. Horellou1,S.Aalto1, F. Combes5, M. Guélin6,7, and C. Henkel8,9 1 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden e-mail: [email protected] 2 Institut d’Astrophysique Spatiale, Bât. 121, Université Paris-Sud, 91405 Orsay Cedex, France 3 Sydney Institute for Astronomy, School of Physics, The University of Sydney, 2006 NSW, Australia 4 ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Australia 5 Observatoire de Paris, LERMA, CNRS, 61 Av. de l’Observatoire, 75014 Paris, France 6 Institut de Radioastronomie Millimétrique, 300 rue de la piscine, 38406 Saint-Martin d’Hères, France 7 École Normale Supérieure/LERMA, 24 rue Lhomond, 75005 Paris, France 8 Max-Planck-Institut für Radioastonomie, Auf dem Hügel 69, 53121 Bonn, Germany 9 Astron. Dept., King Abdulaziz University, PO Box 80203, Jeddah, Saudi Arabia Received 22 October 2012 / Accepted 21 December 2012 ABSTRACT Context. According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model. Aims. We aim to measure the temperature of the CMB with an accuracy of a few percent at z = 0.89 toward the molecular absorber in the galaxy lensing the quasar PKS 1830−211. -
50 Years of the Lovell Telescope Transcript
50 years of the Lovell telescope Transcript Date: Wednesday, 5 December 2007 - 12:00AM 50 YEARS OF THE LOVELL TELESCOPE Professor Ian Morison The Early days at Jodrell Bank In late 1945 Dr Bernard Lovell (as he then was) returned to Manchester University after working on the development of radar during the war years. His aim was to continue his researches into cosmic rays - highly energetic particles that enter the Earth's atmosphere from outer space. He had the idea that sporadic echoes sometimes received by military radars might be the result of cosmic rays entering the atmosphere and thus radar observations might provide a new way to continue his researches. Radar observations were not practical in the centre of Manchester so he took his ex-army radar system out to the University's Botanical Grounds at Jodrell Bank, some 20 miles to the south. By the middle of December 1945, the system was operating and his team was soon able to prove that the echoes were coming not from cosmic rays but from ionized meteor trails left behind when small particles, released from comets, are burnt up in the upper atmosphere of the Earth. Radar Antenna in the Botany Grounds. The Jodrell Bank Experimental Station. The observations continued and, to house the expanding staff and equipment, the Jodrell Bank Experimental Station was built in the field next to the Botanic Grounds. Lovell realised that a much more sensitive radio telescope would be required to detect cosmic rays and so, in 1947, the researchers built a large parabolic reflector, 66-m across, pointing upwards to observe the sky passing overhead. -
The Methods and Experiments of Shape Measurement for Off-Axis
materials Article The Methods and Experiments of Shape Measurement for Off-Axis Conic Aspheric Surface Shijie Li 1,2,*, Jin Zhang 1,2, Weiguo Liu 1,2, Haifeng Liang 1,2, Yi Xie 3 and Xiaoqin Li 4 1 Shaanxi Province Key Laboratory of Thin Film Technology and Optical Test, Xi’an Technological University, Xi’an 710021, China; [email protected] (J.Z.); [email protected] (W.L.); hfl[email protected] (H.L.) 2 School of Optoelectronic Engineering, Xi’an Technological University, Xi’an 710021, China 3 Display Technology Department, Luoyang Institute of Electro-optical Equipment, AVIC, Luoyang 471009, China; [email protected] 4 Library of Xi’an Technological University, Xi’an Technological University, Xi’an 710021, China; [email protected] * Correspondence: [email protected] Received: 26 March 2020; Accepted: 27 April 2020; Published: 1 May 2020 Abstract: The off-axis conic aspheric surface is widely used as a component in modern optical systems. It is critical for this kind of surface to obtain the real accuracy of the shape during optical processing. As is widely known, the null test is an effective method to measure the shape accuracy with high precision. Therefore, three shape measurement methods of null test including auto-collimation, single computer-generated hologram (CGH), and hybrid compensation are presented in detail in this research. Although the various methods have their own advantages and disadvantages, all methods need a special auxiliary component to accomplish the measurement. In the paper, an off-axis paraboloid (OAP) was chosen to be measured using the three methods along with auxiliary components of their own and it was shown that the experimental results involved in peak-to-valley (PV), root-mean-square (RMS), and shape distribution from three methods were consistent. -
CASKAR: a CASPER Concept for the SKA Phase 1 Signal Processing Sub-System
CASKAR: A CASPER concept for the SKA phase 1 Signal Processing Sub-system Francois Kapp, SKA SA Outline • Background • Technical – Architecture – Power • Cost • Schedule • Challenges/Risks • Conclusions Background CASPER Technology MeerKAT Who is CASPER? • Berkeley Wireless Research Center • Nancay Observatory • UC Berkeley Radio Astronomy Lab • Oxford University Astrophysics • UC Berkeley Space Sciences Lab • Metsähovi Radio Observatory, Helsinki University of • Karoo Array Telescope / SKA - SA Technology • NRAO - Green Bank • New Jersey Institute of Technology • NRAO - Socorro • West Virginia University Department of Physics • Allen Telescope Array • University of Iowa Department of Astronomy and • MIT Haystack Observatory Physics • Harvard-Smithsonian Center for Astrophysics • Ohio State University Electroscience Lab • Caltech • Hong Kong University Department of Electrical and Electronic Engineering • Cornell University • Hartebeesthoek Radio Astronomy Observatory • NAIC - Arecibo Observatory • INAF - Istituto di Radioastronomia, Northern Cross • UC Berkeley - Leuschner Observatory Radiotelescope • Giant Metrewave Radio Telescope • University of Manchester, Jodrell Bank Centre for • Institute of Astronomy and Astrophysics, Academia Sinica Astrophysics • National Astronomical Observatories, Chinese Academy of • Submillimeter Array Sciences • NRAO - Tucson / University of Arizona Department of • CSIRO - Australia Telescope National Facility Astronomy • Parkes Observatory • Center for Astrophysics and Supercomputing, Swinburne University -
Maser Observations with New Instruments
Cosmic Masers - from OH to H0 Proceedings IAU Symposium No. 287, 2012 c 2012 International Astronomical Union E. Humphreys & W. Vlemmings, eds. DOI: 00.0000/X000000000000000X Maser observations with new instruments Alwyn Wootten1 1North American ALMA Science Center, NRAOy, 520 Edgemont Rd., Charlottesville, Virginia 22903, USA email: [email protected] Abstract. The Atacama Large Millimeter/submillimeter Array (ALMA)y, and the Jansky Very Large Array (JVLA) have recently begun probing the Universe. Both provide the largest collect- ing area available at locations on a high dry site, endowing them with unparalleled potential for sensitive spectral line observations. Over the next few years, these telescopes will be joined by other telescopes to provide advances in maser science, including NOEMA and the LMT. Other instruments of note for maser science which may commence construction include the North American Array, the CCAT, and an enlarged worldwide VLB network outfitted to operate into the millimeter wavelength regime. Keywords. masers, radio lines: ISM, instrumentation: high angular resolution 1. Introduction At the last IAU Symposium on masers, construction had just begun on the Atacama Large Millimeter/Submillimeter Array (ALMA), the upgrade of the Very Large Array to the Jansky Very Large Array was being planned, and millimeter instrumentation was being introduced on the Green Bank Telescope (GBT). CARMA had just commenced its first semester of routine science and would shortly populate its more extended arrays, enabling high resolution observations, particularly well adapted to maser observations. The Submillimeter Array was forging new paths with high resolution observations up to the edge of the atmospheric windows near 700 GHz. -
The Lovell Telescope … Through Its Surfaces Simon Garrington, JBO/University of Manchester
The Lovell Telescope … through its surfaces Simon Garrington, JBO/University of Manchester • Original design & redesign: 1950-1957 • Radical modification & new surface: 1971 • Replacement of surface: 2001 • Replacement of original Picture A. Holloway surface: 2018 • Other consequences: foundations O1 Original MkI proposal and changes • Concept & proposals: 1950-1 • Lovell-Husband Sep 1949 • Radio Astronomy Cttee 1950 • rail track; towers, cradle, 4-inch mesh • 2-inch mesh/5-in profile by 20 Mar 1951 submission • Design changes • 21cm line discovered (Ewen 25 Mar 1951) • Inner 100’ mesh 1x2-in ‘at no cost’ ? Sep 1952 • Interest from Air Ministry: 10cm radar • March 1954: 3/4-in mesh -> stronger cradle … but Air Ministry step back O2 Original MkI proposal and changes • Concept & proposals: 1950-1 • Lovell-Husband Sep 1949 • Radio Astronomy Cttee 1950 • rail track; towers, cradle, 4-inch mesh • 2-inch mesh/5-in profile by 20 Mar 1951 submission • Design changes • 21cm line discovered (Ewen 25 Mar 1951) • Inner 100’ mesh 1x2-in ‘at no cost’ ? Sep 1952 • Interest from Air Ministry: 10cm radar • March 1954: 3/4-in mesh -> stronger cradle … but Air Ministry step back O3 Original MkI proposal and changes • Concept & proposals: 1950-1 • Lovell-Husband Sep 1949 • Radio Astronomy Cttee 1950 • rail track; towers, cradle, 4-inch mesh • 2-inch mesh/5-in profile by 20 Mar 1951 submission • Design changes • 21cm line discovered (Ewen 25 Mar 1951) • Inner 100’ mesh 1x2-in ‘at no cost’ ? Sep 1952 • Interest from Air Ministry: 10cm radar • March 1954: 3/4-in -
Optical Low-Coherence Interferometry for Selected Technical Applications
BULLETIN OF THE POLISH ACADEMY OF SCIENCES TECHNICAL SCIENCES Vol. 56, No. 2, 2008 Optical low-coherence interferometry for selected technical applications J. PLUCIŃSKI∗, R. HYPSZER, P. WIERZBA, M. STRĄKOWSKI, M. JĘDRZEJEWSKA-SZCZERSKA, M. MACIEJEWSKI, and B.B. KOSMOWSKI Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, 11/12 Narutowicza St., 80-952 Gdańsk, Poland Abstract. Optical low-coherence interferometry is one of the most rapidly advancing measurement techniques. This technique is capable of performing non-contact and non-destructive measurement and can be used not only to measure several quantities, such as temperature, pressure, refractive index, but also for investigation of inner structure of a broad range of technical materials. We present theoretical description of low-coherence interferometry and discuss its unique properties. We describe an OCT system developed in our Department for investigation of the structure of technical materials. In order to provide a better insight into the structure of investigated objects, our system was enhanced to include polarization state analysis capability. Measurement results of highly scattering materials e.g. PLZT ceramics and polymer composites are presented. Moreover, we present measurement setups for temperature, displacement and refractive index measurement using low coherence interferometry. Finally, some advanced detection setups, providing unique benefits, such as noise reduction or extended measurement range, are discussed. Key words: low-coherence interferometry (LCI), optical coherence tomography (OCT), polarization-sensitive OCT (PS-OCT). 1. Introduction 2. Analysis of two-beam interference Low-coherence interferometry (LCI), also known as white- 2.1. Two-beam interference – time domain description. light interferometry (WLI), is an attractive measurement Let us consider interference of two beams emitted from method offering high measurement resolution, high sensi- a quasi-monochromatic light source located at a point P, i.e. -
RESEARCH FACILITIES for the SCIENTIFIC COMMUNITY
NATIONAL RADIO ASTRONOMY OBSERVATORY RESEARCH FACILITIES for the SCIENTIFIC COMMUNITY 2020 Atacama Large Millimeter/submillimeter Array Karl G. Jansky Very Large Array Central Development Laboratory Very Long Baseline Array CONTENTS RESEARCH FACILITIES 2020 NRAO Overview.......................................1 Atacama Large Millimeter/submillimeter Array (ALMA).......2 Very Long Baseline Array (VLBA) .........................6 Karl G. Jansky Very Large Array (VLA)......................8 Central Development Laboratory (CDL)..................14 Student & Visitor Programs ..............................16 (above image) One of the five ngVLA Key Science Goals is Using Pulsars in the Galactic Center to Make a Fundamental Test of Gravity. Pulsars in the Galactic Center represent clocks moving in the space-time potential of a super-massive black hole and would enable qualitatively new tests of theories of gravity. More generally, they offer the opportunity to constrain the history of star formation, stellar dynamics, stellar evolution, and the magneto-ionic medium in the Galactic Center. The ngVLA combination of sensitivity and frequency range will enable it to probe much deeper into the likely Galactic Center pulsar population to address fundamental questions in relativity and stellar evolution. Credit: NRAO/AUI/NSF, S. Dagnello (cover) ALMA antennas. Credit: NRAO/AUI/NSF; ALMA, P. Carrillo (back cover) ALMA map of Jupiter showing the distribution of ammonia gas below Jupiter’s cloud deck. Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello NRAO Overview ALMA photo courtesy of D. Kordan ALMA photo courtesy of D. The National Radio Astronomy Observatory (NRAO) is delivering transformational scientific capabili- ties and operating three world-class telescopes that are enabling the as- tronomy community to address its highest priority science objectives. -
Phase Tomography by X-Ray Talbot Interferometry
Phase Tomography by X-ray Talbot Interferometry X-ray phase imaging is attractive for the beamline of NewSUBARU, SPring-8. A SEM observation of weakly absorbing materials, such as (scanning electron microscope) image of the grating soft materials and biological tissues. In the past is shown in Fig. 1. The pitch and pattern height were decade, several techniques of X-ray phase imaging 8 µm and 30 µm, respectively. were reported and demonstrated [1]. Recently, we Through the quantitative measurement of the have developed an X-ray Talbot interferometer differential phase shift by the sample, extremely high- for novel X-ray phase imaging, including phase sensitive three-dimensional imaging, that is, X-ray tomography. This method is unique in that phase tomography, is attainable by X-ray Talbot transmission gratings are used to generate differential interferometry [3]. We demonstrated this with phase contrast (Fig. 1). Two gratings are aligned biological samples using monochromatic undulator along the optical axis with a specific distance X-rays at beamline BL20XU. Figure 2 shows a rabbit determined by the X-ray wavelength λ and the grating liver tissue with VX2 cancer observed by X-ray phase pitch d. The influence of refraction on the sample tomography using a CCD-based X-ray image detector placed in front of the first grating is observed just whose effective pixel size was 3.14 µm [4]. The behind the second grating. The detailed principle of cancerous lesion is depicted with a darker gray level the contrast generation is described in Refs. [2,3]. than the surrounding normal liver tissue. -
High-Resolution Radio Observations of Submillimetre Galaxies
Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 7 November 2018 (MN LATEX style file v2.2) High-resolution radio observations of submillimetre galaxies A. D. Biggs1⋆ and R.J. Ivison1,2 1UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ 2Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ Accepted 2007 December 17. Received 2007 December 14; in original form 2007 September 11 ABSTRACT We have produced sensitive, high-resolution radio maps of 12 submillimetre (submm) galax- ies (SMGs) in the Lockman Hole using combined Multi-Element Radio-Linked Interferom- eter Network (MERLIN) and Very Large Array (VLA) data at a frequency of 1.4GHz. Inte- grating for 350hr yielded an r.m.s. noise of 6.0 µJybeam−1 and a resolution of 0.2–0.5arcsec. For the first time, wide-field data from the two arrays have been combined in the (u, v) plane and the bandwidthsmearing response of the VLA data has been removed.All of the SMGs are detected in our maps as well as sources comprising a non-submm luminous control sample. We find evidence that SMGs are more extended than the general µJy radio population and that therefore, unlike in local ultraluminous infrared galaxies (ULIRGs), the starburst compo- nent of the radio emission is extended and not confined to the galactic nucleus. For the eight sources with redshifts we measure linear sizes between 1 and 8kpc with a median of 5kpc. Therefore, they are in general larger than local ULIRGs which may support an early-stage merger scenario for the starburst trigger.