Influence of collimator aberrations on the instrument line shape of a Fourier transform spectrometer

The influence of the aberrations of a collimator optical system on the instrument line shape (ILS) of a Fourier transform spectrometer was studied. By analyzing the wave propagation in the spectrometer, numerical distributions of intensity in images of source points visible at different angles from the center of the collimator were modeled. Thus, the shape of the function describing the angular distribution of the intensity in the interferometer was obtained. Then, the ILS of the spectrometer was derived. The influence of the aberration on the ILS was analyzed by determining the shifts of the line positions for different values of third-order aberrations and parameters of the device (field of view and diameter of the aperture). Conclusions concerning the influence of the particular aberrations are presented.