Millimeter-wave antireflection coating for cryogenic silicon lenses.
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.
Lau
Judy
J
Department of Physics, Princeton University, New Jersey 08544, USA.
Fowler
Joseph
J
Marriage
Tobias
T
Page
Lyman
L
Leong
Jon
J
Wishnow
Edward
E
Henry
Ross
R
Wollack
Ed
E
Halpern
Mark
M
Marsden
Danica
D
Marsden
Gaelen
G