提出一种基于空间光调制的光束聚焦控制方法，利用液晶空间光调制器产生动态的二元菲涅耳透镜相位结构，以实现对光束焦斑的轴向与横向偏移的快速精确调节。采用面阵探测器检测光斑大小与位置信息，结合反馈控制机制可实现对光束聚焦点三维位置的自动校准及稳定性控制。该方法在调节过程中不同偏移量之间不存在耦合影响，且横向偏移调节对光传输距离不敏感。进一步介绍了基于该方法搭建的光束聚焦实时反馈控制系统。实验表明，光束焦斑的轴向校准能做到精确快速的收敛。横向偏移校准方面，在较短焦距的情况下能做到单步收敛，而在较长焦距的情况下需要结合比例积分微分控制算法进行调节，如利用数据拟合对调节误差进行经验修正，也可做到单步收敛。

A method of beam focusing control based on the spatial light modulation is proposed. In order to realize the rapid and precise adjustment on the axial and transverse deviations of the beam focusing, the liquid crystal spatial light modulator is adopted to produce the dynamic phase structure of binary Fresnel lens. An area array detector is used to detect the size and position of the light spot. And combining the feedback control mechanism, the automatic calibration and stability control on the beam focus point of three-dimensional position can be realized. In the adjustment process of this method, there is no coupling among different deviations, and the transverse deviation adjustments are insensitive to the propagation distance. Furthermore, the real-time feedback control system of beam focusing based on this method is introduced. The experiment results show that the axial calibration of the beam focal spot can converge precisely and rapidly. The transverse deviation calibration can converge with single step in the case of short focal length. In the case of long focal length, the combination of proportion-integration-differentiation algorithm is need to adjust. The convergence with single step can be also realized if an experiential correction on the adjustment errors based on the data fitting are corrected experimentally.