Aerogel Scattering Filters for Cosmic Microwave Background Observations

Essinger-Hileman, Thomas ; Bennett, Charles L ; Corbett, Lance ; Guo, Haiquan ; Marriage, Tobias ; Meador, Mary Ann B ; Rostem, Karwan ; Wollack, Edward J

关键词: AEROGELS;    APERTURES;    ASTRONOMICAL POLARIMETRY;    BROADBAND;    COSMIC MICROWAVE BACKGROUND RADIATION;    CRYOGENIC EQUIPMENT;    DIELECTRICS;    FABRICATION;    INFRARED FILTERS;    MILLIMETER WAVES;    OPTICAL MEASUREMENT;    PARTICLE SIZE DISTRIBUTION;    REFRACTIVITY;    SCATTERING;    SUBMILLIMETER WAVES;   

RP-ID  :  GSFC-E-DAA-TN67039

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来源: NASA Technical Reports Server

【 摘 要 】

We present the design and performance of broadband and tunable infrared-blocking filters for millimeter and sub-millimeter astronomy composed of small scattering particles embedded in an aerogel substrate. The ultra-low-density (< 100 mg/cu cm) aerogel substrate provides an index of refraction as low as 1.05, removing the need for anti-reflection 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.