title: Application of Doppler Michelson imaging to upper atmospheric wind measurement: WINDII and beyond.
abstract: A solid Doppler Michelson interferometer, consisting of different refractive plates cemented in the two arms of the interferometer, can be designed to be field widened, achromatic, and thermally stable. If the mirror in one arm is allowed to step over one wavelength about a fixed optical path difference, then phase-stepping interferometry can be used to determine the phase of an input spectral line. This is the basis of an optical Doppler interferometer used to measure upper atmospheric winds from space: the wind imaging interferometer (WINDII) on the Upper Atmosphere Research Satellite, UARS, which was launched on 12 September 1991 and is still operating in orbit. The instrument employs a CCD imager to record a sequence of images at different phase steps from which images of optical emission rate, wind, and temperature are derived. The WINDII concept is reviewed, and its implementation is described. The performance in orbit is then reviewed, and a summary of some of the geophysical results is given. Finally, some suggestions for future applications of this concept are presented.
authors.forename: G G
authors.initials: GG
authors.lastname: Shepherd