Response of fourier-transform spectrometers to absorption and emission in a homogeneous single-layered beam splitter.

Thermal self-emission contributes to interferograms measured with Fourier-transform infrared spectrometers. If the beam-splitter is almost transparent, the complex spectral amplitude that is due to the detector port emission is opposite that of the input port, whereas the amplitude that is due to the beam-splitter emission is in quadrature. The situation of an absorbing beam splitter is examined here. The volume beam-splitter emission is modeled by a superposition of dipole sources spread in an absorbing film. Angular polarization correlations are taken into account. It is found that the phase relations between the complex spectral amplitudes are affected. Numerical data are given for experimental conditions adapted to those of the airborne limb sounder MIPAS-FT.

Thermal emission from dielectric beam splitters in michelson interferometers: a schematic analysis.

Thermal emission from beam splitters in Fourier transform infrared spectrometers causes spectral amplitudes that are in quadrature to those of radiation from the field of view or from the detector port. Beam-splitter emission is described as a superposition of radiation of electromagnetic dipoles with angular polarization correlation taken into account for the real refractive index. Surface emission shows characteristic differences compared with volume emission. Numerical data are given for experimental conditions adapted to those of the airborne limb sounder MIPAS-FT.

Correction of phase anomalies of atmospheric emission spectra by the double-differencing method.

Atmospheric emission measurements with the cryogenic airborne Michelson Interferometer for Passive Atmospheric Sounding revealed strongly disturbed phase and magnitude spectra. They were corrected with the double-differencing method: The phase information implied in the line structure of atmospheric spectra is used to specify a phase shift with respect to an instrumental phase spectrum, which was determined once from calibration measurements with the differencing method of Revercomb et al. [Appl. Opt. 27, 3210 (1988)].

Phase corrections for the emission sounder MIPAS-FT.

MIPAS-FT is an airborne Fourier-transform infrared emission sounder. Complex Fourier transformation of two-sided interferograms taken in flight shows strong anomalies in the correction phase, which are eliminated by explicitly taking into account beam-splitter emission. The latter is described mathematically.