光束合成是高功率固体激光器进一步发展的重要途径,其中各子束的相位锁定是实现相干合成的关键。分析了4束矩形光斑在光束合成中子束相位探测方法,建立阵列光束在锁相闭环下的光束合成模型。采用外差法探测子束与参考光束形成的拍频信号,通过异或电路及滤波电路得到直流信号,计算出该子束的相对相位差;将相位差转换为相位调制控制器的驱动电压,从而实现子束的相位闭环控制。利用模型研究了锁相开环、闭环下,不同子束间相位差、随机像差对合成光束远场强度分布的影响。模拟结果显示,锁相闭环下可以实现各子束与参考光束相位一致。另外讨论了影响闭环控制下相位残差的因素。 Beam synthesis is an important way for further development of high power solid-state lasers. The phase locking of each beamlet is the key to achieve coherent synthesis. The method to detect the neutron beam phase of four beams with rectangular beam spot is analyzed, and the beam synthesis model of the array beam under the phase locked loop is established. Using heterodyne method to detect the beat signal formed by the sub-beam and the reference beam, obtaining the direct current signal by the XOR circuit and the filter circuit to calculate the relative phase difference of the sub-beam; converting the phase difference into the driving voltage of the phase modulation controller, In order to achieve closed-loop control of the beam sub-phase. The effects of phase-locked open-loop, closed-loop, phase difference between different beamlets and random aberrations on the far-field intensity distribution of the composite beam were studied by using the model. Simulation results show that the closed-loop can achieve the phase of each beam and the reference beam. In addition, the factors affecting the phase residual under closed-loop control are discussed.