title: Low Temperature Filter for Photometry in the 20-micro Atmospheric Window.
abstract: In a search for a filter for a 20-micro astronomical photometer the reststrahlen reflection of Irtran-1 and a ZnO pellet has been measured at low temperatures in the 15-50-micro range. With a mean reflection of 82% between. 16 micro and 22.3 micro the Irtran-1 material appears to be a efficient low temperature filter suitable for this spectral window, especially when using several reflections.
authors.forename: J J
authors.initials: JJ
authors.lastname: Wijnbergen