Fig. 1. Working principle diagram of optical load

Fig. 2. Initial structure of Cassegrain Telescope

Fig. 3. Layout of plate beam-splitters

Fig. 4. Schematic diagram of on-axis astigmatism introduced by plate beam-splitter

Fig. 5. Schematic diagram of optical axis deviation

Fig. 6. Structure of visible-light imaging module

Fig. 7. MTF curves of the imaging module at different detection distances at −20 ℃. (a) 500 m; (b) 1000 m; (c) 1500 m

Fig. 8. MTF curves of the imaging module at different detection distances at 20 ℃. (a) 500 m; (b) 1000 m; (c) 1500 m

Fig. 9. MTF curves of the imaging module at different detection distances at 50 ℃. (a) 500 m; (b) 1000 m; (c) 1500 m

Fig. 10. Different spectra-receiving refractor group. (a) Ultraviolet refractor group; (b) Visible-light refractor group; (c) Short-wave infrared refractor group

Fig. 11. Structure of the optics system

Fig. 12. Full image heights of each spectral-receiving module with different object distances at extreme temperature

Fig. 13. Aperture angle in image space of each spectral-receiving module with different object distances at extreme temperature

Fig. 14. Results of deformation analysis of primary mirror at extreme temperature. (a) 50 ℃; （b）−20 ℃

Fig. 15. Results of deformation analysis of secondary mirror at extreme temperature. (a) 50 ℃; （b） −20 ℃

Fig. 16. Mechanical structure of the system