Broadband anti-reflective coatings for cosmic microwave background experiments
The desire for higher sensitivity has driven ground-based cosmic microwave background (CMB) experiments to employ ever larger focal planes, which in turn require larger reimaging optics. Practical limits to the maximum size of these optics motivates the development of quasi-optically-coupled (lensle...
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ftosti:oai:osti.gov:1478058 2023-07-30T04:06:55+02:00 Broadband anti-reflective coatings for cosmic microwave background experiments Nadolski, A. 2022-02-02 application/pdf http://www.osti.gov/servlets/purl/1478058 https://www.osti.gov/biblio/1478058 https://doi.org/10.1117/12.2315674 unknown http://www.osti.gov/servlets/purl/1478058 https://www.osti.gov/biblio/1478058 https://doi.org/10.1117/12.2315674 doi:10.1117/12.2315674 79 ASTRONOMY AND ASTROPHYSICS 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY 2022 ftosti https://doi.org/10.1117/12.2315674 2023-07-11T09:29:37Z The desire for higher sensitivity has driven ground-based cosmic microwave background (CMB) experiments to employ ever larger focal planes, which in turn require larger reimaging optics. Practical limits to the maximum size of these optics motivates the development of quasi-optically-coupled (lenslet-coupled), multi-chroic detectors. These detectors can be sensitive across a broader bandwidth compared to waveguide-coupled detectors. However, the increase in bandwidth comes at a cost: the lenses (up to ~700 mm diameter) and lenslets (~5 mm diameter, hemispherical lenses on the focal plane) used in these systems are made from high-refractive-index materials (such as silicon or amorphous aluminum oxide) that reflect nearly a third of the incident radiation. In order to maximize the faint CMB signal that reaches the detectors, the lenses and lenslets must be coated with an anti-reflective (AR) material. The AR coating must maximize radiation transmission in scientifically interesting bands and be cryogenically stable. Such a coating was developed for the third generation camera, SPT-3G, of the South Pole Telescope (SPT) experiment, but the materials and techniques used in the development are general to AR coatings for mm-wave optics. The three-layer polytetra uoroethylene-based AR coating is broadband, inexpensive, and can be manufactured with simple tools. The coating is field tested; AR coated focal plane elements were deployed in the 2016-2017 austral summer and AR coated reimaging optics were deployed in 2017-2018. Other/Unknown Material South pole SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Austral South Pole Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 138 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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79 ASTRONOMY AND ASTROPHYSICS 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY |
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79 ASTRONOMY AND ASTROPHYSICS 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY Nadolski, A. Broadband anti-reflective coatings for cosmic microwave background experiments |
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79 ASTRONOMY AND ASTROPHYSICS 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY |
description |
The desire for higher sensitivity has driven ground-based cosmic microwave background (CMB) experiments to employ ever larger focal planes, which in turn require larger reimaging optics. Practical limits to the maximum size of these optics motivates the development of quasi-optically-coupled (lenslet-coupled), multi-chroic detectors. These detectors can be sensitive across a broader bandwidth compared to waveguide-coupled detectors. However, the increase in bandwidth comes at a cost: the lenses (up to ~700 mm diameter) and lenslets (~5 mm diameter, hemispherical lenses on the focal plane) used in these systems are made from high-refractive-index materials (such as silicon or amorphous aluminum oxide) that reflect nearly a third of the incident radiation. In order to maximize the faint CMB signal that reaches the detectors, the lenses and lenslets must be coated with an anti-reflective (AR) material. The AR coating must maximize radiation transmission in scientifically interesting bands and be cryogenically stable. Such a coating was developed for the third generation camera, SPT-3G, of the South Pole Telescope (SPT) experiment, but the materials and techniques used in the development are general to AR coatings for mm-wave optics. The three-layer polytetra uoroethylene-based AR coating is broadband, inexpensive, and can be manufactured with simple tools. The coating is field tested; AR coated focal plane elements were deployed in the 2016-2017 austral summer and AR coated reimaging optics were deployed in 2017-2018. |
author |
Nadolski, A. |
author_facet |
Nadolski, A. |
author_sort |
Nadolski, A. |
title |
Broadband anti-reflective coatings for cosmic microwave background experiments |
title_short |
Broadband anti-reflective coatings for cosmic microwave background experiments |
title_full |
Broadband anti-reflective coatings for cosmic microwave background experiments |
title_fullStr |
Broadband anti-reflective coatings for cosmic microwave background experiments |
title_full_unstemmed |
Broadband anti-reflective coatings for cosmic microwave background experiments |
title_sort |
broadband anti-reflective coatings for cosmic microwave background experiments |
publishDate |
2022 |
url |
http://www.osti.gov/servlets/purl/1478058 https://www.osti.gov/biblio/1478058 https://doi.org/10.1117/12.2315674 |
geographic |
Austral South Pole |
geographic_facet |
Austral South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
http://www.osti.gov/servlets/purl/1478058 https://www.osti.gov/biblio/1478058 https://doi.org/10.1117/12.2315674 doi:10.1117/12.2315674 |
op_doi |
https://doi.org/10.1117/12.2315674 |
container_title |
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX |
container_start_page |
138 |
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1772819869850402816 |