Abstract

We present the design and performance of broadband and tunable infrared-blocking filters for millimeter and submillimeter astronomy composed of small scattering particles embedded in an aerogel substrate. The ultralow-density (typically ${\lt}150\;{\rm mg}/{{\rm cm}^3}$) aerogel substrate provides an index of refraction as low as 1.05, removing the need for antireflection coatings and allowing for broadband operation from DC to above 1 THz. The size distribution of the scattering particles can be tuned to provide a variable cutoff frequency. Aerogel filters with embedded high-resistivity silicon powder are being produced at 40 cm diameter to enable large-aperture cryogenic receivers for cosmic microwave background polarimeters, which require large arrays of sub-Kelvin detectors in their search for the signature of an inflationary gravitational-wave background.

Three-mirror anastigmat for cosmic microwave background observations

S. Padin
Appl. Opt. 57(9) 2314-2326 (2018)

Fabrication of a monolithic 5 m aluminum reflector for millimeter-wavelength observations of the cosmic microwave background

Tyler Natoli, Bradford Benson, John Carlstrom, Eric Chauvin, Bruno Clavel, Nick Emerson, Patricio Gallardo, Mike Niemack, Steve Padin, Klaus Schwab, Lutz Stenvers, and Jeff Zivick
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Scattering and absorption coefficients of silica-doped alumina aerogels

Tairan Fu, Jiaqi Tang, Kai Chen, and Fan Zhang
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Geometrical and physical optics analysis for mm-wavelength refractor telescopes designed to map the cosmic microwave background

Jon E. Gudmundsson
Appl. Opt. 59(11) 3324-3339 (2020)

Sidelobe modeling and mitigation for a three mirror anastigmat cosmic microwave background telescope

Ian Gullett, Bradford Benson, Robert Besuner, Richard Bihary, John Carlstrom, Nick Emerson, Patricio A. Gallardo, Jillian Gomez, Cesiley L. King, Jeff McMahon, Jared L. May, Johanna M. Nagy, Tyler Natoli, Michael D. Niemack, Kate Okun, Stephen Padin, John E. Ruhl, Edward J. Wollack, and Jeff Zivick
Appl. Opt. 62(16) 4334-4341 (2023)