利用波前传感器对光束进行净化的自适应光学系统是目前提高光束质量的常用技术，但在实际应用中，该技术需要波前传感器，系统复杂，体积庞大，同时需要较高性能信标源。为解决上述问题，提出了一种基于变形镜本征模式和远场光斑特征分析的无波前自适应光学系统，用于校正激光器输出的方形光束。将变形镜影响函数进行本征模式分解，并用远场光斑的均方半径作为评价函数，建立了畸变波前的模式系数与评价函数之间的关系，通过测量评价函数获得模式系数用于求解校正电压，实现波前共轭校正。仿真校正和实验验证结果表明，该方法可以有效实现静态像差校正，提高远场光斑的能量集中度。

Wavefront sensor-based beam cleanup adaptive optical system is the main equiment to improve the beam quality of high-energy laser systems. However, the system is complicated and bulky because it requires to measure wavefront and needs a strong beacon source. To solve the above problems, this paper proposes a wavefront sensorless adaptive optical system which utilizes the deformable-mirror eigen modes and the characteristics of the far-field spot for processing and analyzing thus to correct the square beam. The eigenmode decomposition of the deformable mirror’s influnce function is used, and the mean square radius of the far-field spot is used as the metric function. The relationship between the eigenmode coefficient of the wavefront and the metric function is established. The measurement of the metric function is used to calculate voltage. Simulation analysis and experimental verification of the correction method show that the method can effectively achieve the correction of static aberrations and improve the energy concentration of the far-field spot.