Fig. 1. Focusing schematic of high-NA objective lens

Fig. 2. Design of phase plate. (a) Schematic of phase distribution; (b) principle of genetic algorithm

Fig. 3. Phase patterns of multiple focal spots and corresponding intensity distributions in focal plane with different non-orthogonal arrays

Fig. 4. Schematic of the experimental setup. (a) Schematic of manufacturing process for binary phase plate; (b) microscopy image of phase plate; (c) experimental result of focal-spot array; (d) schematic of experimental light path

Fig. 5. Intensity distributions of 3×3 focal spots with different inclination angles in focal plane and corresponding experimental results of optical trapping for silica microspheres

Fig. 6. Intensity distributions of 5×5 focal spots with different inclination angles in focal plane and corresponding experimental results of optical trapping for silica microspheres