Time-Resolving Infrared Polarization Analyzer for the 2- to 4-μ Range

Abstract

A polarization analyzer for time‐resolved rotation measurements of polarized infrared radiation from 2‐ to 4‐μ wavelength is described. The instrument employs air‐germanium interfaces, uncooled InAs photovoltaic detectors, and 10‐Mc‐bandwidth low noise preamplifiers. Angular resolution of approximately ½° for polarization oscillations as high as 1 Mc is obtained for ½‐mW emission from a He‐Ne maser at 3.39 μ. It is useful, with reduced resolution, up to 10 Mc; the resolution can be improved through reduced preamplifier bandwidth for below 1 Mc. Application of the instrument to measurement of the Faraday rotation of a 3.39‐μ polarized maser beam propagated through a dense, high temperature, deuterium plasma in an intense magnetic field is discussed.