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.