Patent ID: 8345256

Claim:
A method for elaborating an interferogram at an instrument, where the instrument having an input spectrum, comprising the steps of: determining the gain variations among pixels of a detection array of the instrument according to the steps of: elaborating a first interferogram by creating a finite number of optical path differences, and elaborating at least two shifted interferograms by shifting each of the optical path differences of the first interferogram, where each optical path difference having at least three samples positioned on a sine wave portion; determining, for each sine wave portion, a function coinciding with the sine wave portion by interpolation; determining a calibration coefficient for each optical path difference from the function coinciding with the sine wave portion corresponding to this optical path difference; detecting an image of the first interferogram by the detection array of the instrument; and producing a corrected image of the first interferogram, which producing comprises using said calibration coefficients to correct the image of the first interferogram to thereby reduce the effects of errors caused by gain variations among the pixels of the detection array.