Modeling of Responsivity and Self-Emission of a Double-Beam Fourier-Transform Infrared Interferometer


  1. Theriault, J-M.
Corporate Authors
Defence Research Establishment Valcartier, Valcartier QUE (CAN)
A modeling study aimed at characterizing the radiometric properties of a double-beam Fourier-transform infrared interferometer is presented. Measurements showed that the two responsivities associated with each interferometer channel are different in certain spectral regions. This anomally was attributed to a dissymmetry between the optical transmissions of the two plates that form the beam splitter. This dissymmetry is primarily responsible for the instrument residual emission. A secondary cause of residual emission is attributed to the relative alignment of the two input optics. Both effects were taken into account in a model that gives the instrument residual emission in terms of the beam splitter temperature. Actual results indicate that in the 7-14-mu m window the instrument residual emission can be modeled with an absolute radiometric error smaller than 0.5 K (blackbody at 290 K). The model was used to develop an automatic calibration procedure that yields radiance errors smaller than 0.05 mu W/cm square sr cm 1(-) in the 7-14-mu m band. The radiometric stability of the interferometer was analysed.
Fourier transform infrared (FTIR) spectrometry;Beam splitting
Date of publication
01 Jan 1999
Number of Pages
Reprinted from
Applied Optics, vol 38, no 3, 1999, p 507-515
Hardcopy;Document Image stored on Optical Disk

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