Precise reconstruction of gas spectrum obtained with a birefringent interferometer

In Fourier transform spectroscopy, the use of birefringent materials allows to realize compact spectrometers without moving parts. Nevertheless, to reconstruct an accurate spectrum, one must take into account two important characteristics. First of all, one must consider the wavelength dependence on the refractive indices that produces a distortion of the spectrum abscise axis. A calibration procedure is proposed in this paper, rectifying this point. Then, one must consider the nonlinear dependence on the optical path difference with the position on the CCD sensor that prohibits the direct computation of the spectrum. A pre-processing method is suggested in order to offset this non-linearity. Some experimental results support our matter