利用微透镜列阵实现光束的分割和叠加是一种典型的光束匀化方法。而在微透镜列阵实现激光光束匀化时, 由于微透镜列阵的周期性和激光的相干性, 匀化光斑会产生周期性点阵分布现象, 降低了光束匀化质量。提出一种利用中心离轴型随机微透镜列阵消除点阵效应以实现激光光束的匀化方法。在分析光束经过微透镜列阵的传播特性基础上, 设计列阵中各个子透镜单元的几何中心偏离其光轴, 利用中心离轴量的随机性打破微透镜列阵的周期性, 消除目标面处的点阵现象, 实现高均匀性的光斑分布。采用移动掩模技术制备随机微透镜列阵, 并开展激光光束匀化实验。结果表明, 该方法能够有效提高激光光束的均匀性, 有望在激光加工、医疗和照明等方向有较大的应用前景。

The typical beam homogenization method is based on the microlens array which can realize the segmentation and segistration of the beam. During the laser beam homogenization, the phenomenon of a periodic dot matrix distribution on the target surface will appear because of the periodicity of the microlens array and the coherence of the laser, which reduces the homogenization of the final spot. The random microlens array structure is proposed to achieve the elimination of dot matrix effects in laser beam homogenization. For the analysis of the beam propagation characteristics in the microlens array, the distribution of the geometric center of every sub lens unit are designed randomly off-axis. So the periodicity of the microlens array is disrupted. Therefore, the dot matrix effects on the target surface are eliminated to achieve an ultimate uniform spot. The preparation of the random microlens array has been carried out by the moving mask technology and the corresponding experiments have been developed. The results show that this method can effectively improve the uniformity of the laser beam, which can be used in laser processing, medical treatment and illumination.