Abstract

Gas filter correlation radiometers (GFCR's) have made important contributions to our knowledge of the atmosphere by providing remote atmospheric measurements from a variety of platforms including aircraft¹, and spacecraft². Though GFCR's have many attractive features including high spectral resolution, large etendu and the capability to detect many gas species, these instruments are generally mechanically complex requiring rapidly rotating gas cells or light choppers. A new GFCR concept is being investigated that uses a polarization modulator in conjunction with polarization sensitive beamsplitters as a solid-state "optical switch" to rapidly alternate the path of incoming radiation between the two GFCR optical paths (i.e., the paths containing the gas correlation and vacuum cells). Compared to more conventional GFCR's, this new approach has potential advantages including: (1) long operational life since rapidly moving mechanical parts are not required (an important consideration for spaceborne applications), and (2) a high detection frequency (≈ 100 kHz) which, for a NADIR viewing GFCR, freezes the radiometer's view of the Earth and minimizes other 1/f noise sources.

© 1990 Optical Society of America