Generation of flat-top focal fields using spatially uniform linear source antenna arrays

In a 4Pi focusing system, this paper proposes a method for constructing flat-top optical focus fields based on the radiation pattern of a spatially uniform line source antenna array. The approach employs a genetic algorithm to optimize key parameters of the antenna array, thereby enabling adjustable length and width as well as controllable spatial orientation of the resulting flat-top focus field. Compared with traditional optical field modulation techniques, this method avoids the complexity of optical system design while offering greater degrees of freedom in field shaping. Numerical results demonstrate that the optimized flat-top focus field exhibits high intensity uniformity exceeding 90% within the defined boundary, indicating a significant advantage in maintaining uniform energy distribution. The proposed focus field provides theoretical support and technical potential for applications such as precision laser fabrication, optical trapping, and high-resolution microscopy.