SWIFT instrument testbed for stratospheric wind measurements

The Stratospheric Wind Interferometer for Transport Studies is a limb viewing satellite instrument which is intended to measure stratospheric wind velocities in the altitude range of 20 to 40 km. Tandem etalon filters made of Germanium and a field-widened Michelson interferometer operating in mid- infrared are major components of this instrument. A He-Ne laser and a CCD camera were used to observe Haidinger and Fizeau fringes in visible light and compare their characteristics with mid-infrared measurements. The Fizeau fringes in the visible can be used to observe the irregularities in the Michelson interferometer's path difference. In addition a CO 2 laser operating at 9.26 micrometers has been used to test the Michelson interferometer and the filters together. The filters are thermally tuned to the CO 2 laser line and the filter output was incident on a diffuse surface in front of the Michelson input aperture. The Michelson interferometer was then pressure scanned to observe its performance in combination with the filters.