Fig. 1. Echelle spectrometer path structure(reflective and transmissive structures)

Fig. 2. Schematic diagram of the two-dimensional spectrum in the free spectral region^[34]

Fig. 3. Schematic diagrams of the spectral reduction process. (a) Original spectra, containing the correspondence between light intensity and position coordinates; (b) spectral reduction model, containing the correspondence between wavelength and position coordinates; (c) spectral calibration results, correspondence between light intensity (vertical direction) and wavelength (horizontal direction), the red arrow indicates the reduction process for a spot corresponding to the wavelength

Fig. 4. Fitting principle of spectral restoration process^[45]

Fig. 5. Schematic diagrams of deviation method. (a) Actual optical path diagram; (b) equivalent model light path diagram

Fig. 6. Mathematical model of main dispersion direction

Fig. 7. Mathematical model of transverse dispersion direction

Fig. 8. Spectral diagram of two monochromatic light^[85](horizontal direction represents different wavelength levels, vertical direction represents different wavelengths)