Author Affiliations
School of Mathematics and Physics, Anhui University of Technology, Maanshan, Anhui 243032, Chinashow less
Fig. 1. Schematic for calculation of focal field
Fig. 2. Light intensity distribution in focal plane for two-ring structure
Fig. 3. Light intensity distributions in focal plane for three-ring structure. (a) R=5.65λ; (b) R=2.85λ
Fig. 4. Light intensity distributions in focal plane for different ring structures. (a) 2-ring; (b) 3-ring; (c) 4-ring; (d) 5-ring; (e) 6-ring
Fig. 5. R, M, S in focal plane versus NA. (a) R value for 4-ring; (b) R value for 5-ring; (c) S and M values for 4-ring; (d) S and M values for 5-ring
Fig. 6. Light intensity distributions in axial direction for different ring structures. (a) 2-ring; (b) 3-ring; (c) 4-ring; (d) 5-ring; (e) 6-ring
Fig. 7. R, M, S in axial direction versus NA. (a) R value for 4-ring; (b) R value for 5-ring; (c) S and M values for 4-ring; (d) S and M values for 5-ring
Number of rings | Relation among normalized ring radii |
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2 | 2-1=0 | 3 | 2(-)+1=0 | 4 | 2(-+)-1=0 | 5 | 2(-+-)+1=0 | 6 | 2(-+-+)-1=0 |
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Table 1. Radius of each ring when generating hollow focal field
ρ1 | ρ2 | R /λ | S | M |
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0.35 | 0.789 | 5.649 | 0.065 | 0.208 | 0.69 | 0.988 | 2.92 | 0.098 | 0.288 | 0.01 | 0.707 | 2.845 | 0.108 | 0.287 |
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Table 2. Optimized three-ring structure
ρ1 | ρ2 | ρ3 | R /λ | S | M |
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0.6 | 0.73 | 0.82 | 2.88 | 0.07 | 0.12 | 0.58 | 0.69 | 0.80 | 2.84 | 0.07 | 0.12 | 0.57 | 0.70 | 0.816 | 2.88 | 0.065 | 0.12 | 0.55 | 0.65 | 0.787 | 2.84 | 0.07 | 0.11 |
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Table 3. Optimized four-ring structure
ρ1 | ρ2 | ρ3 | ρ4 | R /λ | S | M |
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0.36 | 0.68 | 0.72 | 0.828 | 5.52 | 0.05 | 0.15 | 0.54 | 0.64 | 0.76 | 0.98 | 3.01 | 0.060 | 0.11 | 0.55 | 0.66 | 0.77 | 0.98 | 3.01 | 0.059 | 0.10 | 0.56 | 0.67 | 0.78 | 0.98 | 2.91 | 0.064 | 0.11 |
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Table 4. Optimized five-ring structure
ρ1 | ρ2 | ρ3 | ρ4 | ρ5 | R /λ | S | M |
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0.40 | 0.41 | 0.60 | 0.73 | 0.83 | 2.91 | 0.066 | 0.10 | 0.39 | 0.40 | 0.58 | 0.69 | 0.80 | 2.81 | 0.066 | 0.10 | 0.49 | 0.50 | 0.60 | 0.71 | 0.81 | 2.91 | 0.071 | 0.11 | 0.50 | 0.51 | 0.61 | 0.73 | 0.82 | 2.91 | 0.071 | 0.11 |
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Table 5. Optimized six-ring structure
Number of rings | ρ1 | ρ2 | ρ3 | ρ4 | ρ5 | R /λ | S | M |
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2 | 0.707 | | | | | 37.046 | 0.525 | 0.088 | 3 | 0.01 | 0.707 | | | | 37.036 | 0.525 | 0.088 | 4 | 0.59 | 0.65 | 0.758 | | | 35.034 | 0.392 | 0.153 | 5 | 0.56 | 0.62 | 0.73 | 0.981 | | 38.037 | 0.332 | 0.174 | 6 | 0.5 | 0.54 | 0.69 | 0.73 | 0.774 | 35.284 | 0.376 | 0.079 |
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Table 6. Ring radii and R, S, M values corresponding to Fig. 6