Simple spectral reduction algorithm used for the echelle spectrometer.
The structure of the echelle spectrometer equipped with a prism cross-dispersion element is very complex because of the nonlinear interaction between the prism and the echelle grating, which makes it difficult to extract the wavelength information from the two-dimensional spectrogram. According to the dispersion equations of both the grating and the prism direction, a wavelength calibration model is derived, establishing a relationship between the pixel position and the wavelength. It is found that a calibration process is always needed in repeated experiments due to the slight change of the spectrometer parameters caused by the environment. To solve this problem and improve the accuracy of the reduction, a simple spectral reduction algorithm involving calibration and compensation is proposed, which combines the least-square method and the polynomial fitting method. The algorithm was implemented with LabVIEW software, and the result showed that the absolute error of each wavelength was less than 0.02 nm.