Fig. 1. Diffraction imaging elements

Fig. 2. Multistage imaging characteristics of FZP and theoretical value of diffraction efficiency

Fig. 3. Flow chart of SPGD algorithm

Fig. 4. Flow chart of SA

Fig. 5. Diffraction efficiency measurement experiment of FZP

Fig. 6. Experimental diffraction efficiency of FZP

Fig. 7. Extended target imaging experiment of FZP

Fig. 8. The PSF₀ of two-order FZP imaging system

Fig. 9. Extended target imaging image of FZP

Fig. 10. Extended target image for iterative optimization

Fig. 11. The PSF_m obtained by iterative optimization

Fig. 12. The recovery results of SPGD algorithm

Fig. 13. The recovery results of SA

Fig. 14. Local magnification and comparison of restoration result

Fig. 15. Comparison of performance indexes before and after restoration