Fig. 1. Principle of far-field super-resolution bifocal focusing based on spatial light modulator

Fig. 2. Flowchart of optimized design for bifocal super-oscillatory mask

Fig. 3. Optimized SOM phase control distributions. (a) Schematic diagrams of bifocal phase distribution generated using Boolean logic “AND” operation; phase distributions of single-focus and bifocal super-oscillatory masks at radii of (b) 0‒1000λ, (c) 1000λ‒2000λ, (d) 2000λ‒4000λ; (e) 3000λ‒4000λ

Fig. 4. Propagation direction results under theoretical design. (a) Light field intensities for S-SOM₁, S-SOM₂ and B-SOM along propagation direction; (b) maximum intensity distribution along propagation direction for B-SOM; (c) lateral full width at half maximum within longitudinal full width at half maximum for B-SOM

Fig. 5. Focal plane results under theoretical design for B-SOM. Focal plane light field intensities at peak positions of B-SOM at (a) f1'=281600λ and (b) f2'=297000λ; light field intensity curves along radial direction through center of focal spot at peak positions of B-SOM at (c) f1'=281600λ and (d) f2'=297000λ

Fig. 6. Schematic diagram of far-field super-resolution bifocal focusing and measurement platform based on spatial light modulator

Fig. 7. Experimental test results along propagation direction. Light field intensities along propagation direction for (a) S-SOM₁, (b) S-SOM₂, and (c) B-SOM; peak intensities of focal spots along propagation direction for (d) S-SOM₁, (e) S-SOM₂, and (f) B-SOM; lateral full widths at half maximum within longitudinal full width at half maximum range for (g) S-SOM₁, (h) S-SOM₂, and (i) B-SOM

Fig. 8. Experimental test results of light field sections. Light field intensities in xy planes at focal spot peaks for (a) S-SOM₁ and (b) S-SOM₂; light field intensities in xy planes at focal spot peaks for (c)(d) two focal points (B-SOM₁ and B-SOM₂) of B-SOM; (e)‒(h) corresponding intensity distribution curves