Fig. 1. Function and composition diagram of MIRUS

Fig. 2. Optical layout of MIRUS

Fig. 3. MTF of optical system@7 lp/mm. (a) 0.670 μm; (b) 0.725 μm; (c) 0.780 μm

Fig. 4. Spot diagrams on different parts of FOV

Fig. 5. Spectral slit function. (a)‒(c) (0, 0), (0.805, 0), (1.500, 0) field of view at 0.670 μm; (d)‒(f) (0, 0), (0.805, 0), (1.500, 0) field of view at 0.725 μm; (g)‒(i) (0, 0), (0.805, 0), (1.500, 0) field of view at 0.780 μm

Fig. 6. Diffraction efficiency of different blazing angles and anti-blazing angles. (a) TE polarization; (b) TM polarization; (c) no polarization

Fig. 7. Diffraction efficiency of optimized grating

Fig. 8. Layout of the spectrometer

Fig. 9. Instrument line shape (ILS) for different wavelengths. (a) 673.5 nm; (b) 725.0 nm; (c) 779.0 nm

Fig. 10. FWHM for different wavelengths

Fig. 11. Smile for different wavelengths

Fig. 12. Keystone for different wavelength bands

Fig. 13. SNR for different wavelength bands

Fig. 14. Performance evaluation flow chart of MIRUS

Fig. 15. Radiance performance of MIRUS. (a) Simulated typical entrance pupil radiance; (b) SNR under typical radiance conditions

Fig. 16. SNR of SIFIS

Fig. 17. Retrieval accuracy of SIFIS. (a) ${\sigma }_{\mathrm{F}\mathrm{s}}$ for different radiance; (b) relative error for different SNR

Fig. 18. Retrieval accuracy of MIRUS. (a) GSD is 100 m; (b) GSD is 200 m