Fig. 1. The optics designed for the solar FUV-UV spectrometer

Fig. 2. The spectrum estimated by the physical models

Fig. 3. The simulation model of the optics by ZEMAX

Fig. 4. A plane detector is placed for the simulation purpose， the detector in this figure shows 1/6 of the sensors for the full wavelength range

Fig. 5. Spot diagram

Fig. 6. The wave-front of the optics without spectrum focusing mirror

Fig. 7. The wave-front of the optics with spectrum focusing mirror

Fig. 8. The simulation of stray-light suppress and the trap for 0-order spot

Fig. 9. The higher-order diffraction of shorter-wavelength spectrum overlapped with the first-order of the longer-wavelength spectrum

Fig. 10. The transmission efficiency of a band-pass wavelength filter provided