title: Millimeter-wave antireflection coating for cryogenic silicon lenses.
abstract: We have developed and tested an antireflection (AR) coating method for silicon lenses used at cryogenic temperatures and millimeter wavelengths. Our particular application is a measurement of the cosmic microwave background. The coating consists of machined pieces of Cirlex glued to the silicon. The measured reflection from an AR-coated flat piece is less than 1.5% at the design wavelength. The coating has been applied to flats and lenses and has survived multiple thermal cycles from 300 to 4 K. We present the manufacturing method, the material properties, the tests performed, and estimates of the loss that can be achieved in practical lenses.
authors.affiliation: Department of Physics, Princeton University, New Jersey 08544, USA.
authors.forename: Judy
authors.initials: J
authors.lastname: Lau
authors.forename: Joseph
authors.initials: J
authors.lastname: Fowler
authors.forename: Tobias
authors.initials: T
authors.lastname: Marriage
authors.forename: Lyman
authors.initials: L
authors.lastname: Page
authors.forename: Jon
authors.initials: J
authors.lastname: Leong
authors.forename: Edward
authors.initials: E
authors.lastname: Wishnow
authors.forename: Ross
authors.initials: R
authors.lastname: Henry
authors.forename: Ed
authors.initials: E
authors.lastname: Wollack
authors.forename: Mark
authors.initials: M
authors.lastname: Halpern
authors.forename: Danica
authors.initials: D
authors.lastname: Marsden
authors.forename: Gaelen
authors.initials: G
authors.lastname: Marsden