Fig. 1. Diagram of forward-squint strip-map imaging and DBS imaging mode

Fig. 2. SAL transmissive diffractive optical system and collimator feeder

Fig. 3. One-transmitting and four-receiving feeder layout

Fig. 4. Transmitting and receiving field-of-view formed by one-transmitting and four-receiving

Fig. 5. Geometric model of planar diffractive optical system

Fig. 6. Folded phase curve and beam pattern of diffractive primary mirror. (a) Phase curve without fold; (b) phase curve folded by 2π; (c) beam pattern in ±60° range; (d) beam pattern in ±0.01° range

Fig. 7. Phase curve and beam pattern of primary mirror after four quantization. (a) Phase curve of central radiation unit; (b) phase curve of left radiation unit; (c) beam pattern in ±60° range; (d) beam pattern in ±0.01° range

Fig. 8. Planar diffractive optical system

Fig. 9. Diagram of optical system for frequency scanning to achieve beam scanning

Fig. 10. Beam pattern corresponding to different wavelengths. (a) 1.0140 μm; (b) 1.0640 μm; (c) 1.1140 μm

Fig. 11. Diagram of optical system for frequency scanning to achieve beam scanning when focus deviates from axis of main mirror

Fig. 12. Beam pattern when wavelengths are 1.0133, 1.0640, and 1.1200 μm

Fig. 13. Beam pattern when wavelengths are 0.9672, 1.0640 and 1.1822 μm

Fig. 14. Beam pattern corresponding to different wavelengths. (a)(b) 1.0640 μm; (c)(d) 1.0638 μm; (e)(f) 1.0636 μm

Fig. 15. Geometric model of curved-conformal diffractive optical system

Fig. 16. Phase curve and beam pattern of curved-conformal diffractive primary mirror. (a) Phase curve without fold; (b) beam pattern in ±60° range; (c) beam pattern in ±0.01° range

Fig. 17. Wave path difference and phase error between curved-conformal diffractive primary mirror and planar primary mirror. (a) Wave path difference; (b) phase error

Fig. 18. Optical path diagram of laser beam one-dimensional frequency scanning

Fig. 19. Optical path diagram of curved-conformal diffractive optical system for laser beam two-dimensional scanning