Improvements in ALMA Band 10 Optics: Influence of IR Filters and Solutions

Author

Gonzalez, Adriana ; Uzawa, Y. ; Kaneko, Kunihiko ; Saito, Sakuyoshi ; Fujii, Yuka

Author_Institution

Nat. Astron. Obs. of Japan (NAOJ), Tokyo, Japan

Volume

3

Issue

1

fYear

2013

fDate

Jan. 2013

Firstpage

50

Lastpage

55

Abstract

Infrared (IR) filters and cryostat window in the Atacama large millimeter/submillimeter array (ALMA) cryostat were found to greatly degrade the optical performance of ALMA band 10 optics. This degradation has its origin in the reflection the beam suffers when going through the filters and window. The cause and mechanism of this degradation were identified using THz-TDS and simple analysis techniques and a simple solution was found. The proposed solution is based on corrugated horns with chamfered rims and Terahertz absorber paint applied around the horns. This solution proves efficient in keeping the original optical performance when the optics is used in real operation at cryogenic temperature.

Keywords

cryostats; microwave photonics; mirrors; optical arrays; optical design techniques; optical filters; optical windows; reflection; terahertz waves; ALMA band 10 optics; Atacama large millimeter-submillimeter array; THz-TDS method; beam reflection; chamfered rims; corrugated horns; cryogenic temperature; cryostat window; infrared filters; mirrors; optical design techniques; terahertz absorber paint; Apertures; Extraterrestrial measurements; Optical variables measurement; Optics; Paints; Temperature measurement; Transmission line measurements; Atacama large millimeter/submillimeter array; Gaussian beams; submillimeter-wave measurements; submillimeter-wave technology;

fLanguage

English

Journal_Title

Terahertz Science and Technology, IEEE Transactions on

Publisher

ieee

ISSN

2156-342X

Type

jour

DOI

10.1109/TTHZ.2012.2235526

Filename

6413303