As the impact of the instrument internal error, external interference and other factors, the interferogram measured by
Fourier transform spectrometer is asymmetric, result in the complex outcome after Fourier transform. Currently, most
radiometric calibration method used for Fourier transform spectrometer is usually based on real spectrums, which is
converted from the above complex spectrum by calculating magnitude value or make the phase correction first.
Proceed from error sources and mechanisms of the Fourier transform spectrometer, we propose a multi-point radiometric
calibration method based on complex spectral data to improve the processing efficiency and accuracy, which is obtained
by the original interferogram via Fourier transform. We solving the instrument response function include linear gain and
offset by complex spectrum above to calculate complex spectral radiance.
Compared with the traditional method based on real spectrum, the present efficient method does not limited to real
spectrum and the phase correction is not required. In this paper, we use BOMEM's MR304 Fourier transform infrared
spectrometer and the DCN1000N3 blackbody made by HGH Infrared Systems to carry out the radiation calibration
experiment in laboratory. The results show that, the amplitude of complex radiance spectrum obtained by this method
has a high consistency with the theoretical value, while the extra imaginary spectrum is similar with the difference
between results and theoretical value in absolute value and trends. It proved that, this multi-point radiometric calibration
method by using the amplitude of complex spectral data is highly reliable; meanwhile, the imaginary spectrum can
reflect the calibration error very well and offer a new technical approach for accuracy evaluation research.