Fig. 1. Traditional Fresnel zone plates. (a) Schematic diagram of structure; (b) schematic diagram of imaging

Fig. 2. Normalized intensity distribution of HGBs of order m=1, 3, and 6

Fig. 3. Normalized equivalent pupil function of HGBs of order m=1, 3, and 6

Fig. 4. Design parameters of zone plates. (a) Distance between center of rings and center of TFZP; (b) width of rings of zone plates to produce HGBs of order m=1, 3, and 6 and TFZP, respectively

Fig. 5. Simulation of light field on focal plane. (a) Normalized intensity profile on focal plane obtained from ring diffraction model and equivalent pupil function model, respectively; (b) hollow focal spot patterns of these three zone plates

Fig. 6. Structure parameters and dark spot size of zone plates with different wavelengths. (a) Center position of rings; (b) width of rings; (c) ratio of width of rings for different wavelengths compared to that for 3 nm; (d) normalized intensity distribution of hollow Gaussian beams

Fig. 7. Light field intensity on focal plane that has random error. (a) Error value of the rings; (b) focal plane lightfield normalized intensity of the zone plate (inset is logarithmic diagram of the central part)