Interferometric performance analysis of a geostationary sounder

Various efforts are underway to improve meteorological sounding measurements. One such effort is the development of the GOES High Resolution Interferometer Sounder instrument. This instrument has the potential to enhance these measurements by providing higher spectral resolution and simultaneous broadband coverage. This instrument consists of a Fourier Transform Spectrometer (FTS). The heart of this FTS is a Michelson interferometer. The degree to which the sounding performance is enhanced depends crucially on the performance of this interferometer. A system performance analysis of this interferometer is presented. The analysis is based on the MIT Lincoln Labs design of the GHIS instrument. In the analysis, the interferometric modulation as a function of key system parameters is calculated. These parameters include the following: finite field of view, wavefront shear, tilt of interferometer elements, and multiple reflections in the beamsplitter. The impact of modulation changes on the spectral performance is computed by taking an appropriate fourier transform.