为了探究高功率连续激光作用下CCD的损伤特性随时间的演化规律, 根据其结构特点和工作原理, 建立了1.06 μm连续激光辐照CCD的六层结构热力耦合三维模型。综合考虑了微透镜聚焦和铝膜开口率等因素的影响, 通过改变CCD不同损伤阶段的激光辐照方式, 数值模拟分析了CCD多层结构的层层损伤机理, 研究了CCD各个损伤阶段的时间阈值, 并与实验结果进行了对比。结果表明, 微透镜聚焦光束阶段, 微透镜由于熔点较低, 发生熔融分解, CCD表现为点损伤; 微透镜熔融阶段, 失去聚光能力, 在应力损伤和熔融损伤共同作用下, 铝膜层熔融剥落, 表现为纵向亮线损伤; 铝膜层熔融剥落阶段, 激光直接辐照在硅电极上, 硅电极上表面熔融, 造成布线电路的损伤, 导致部分像元中的电荷无法转移, 出现横向暗线损伤; 最后, SiO2绝缘层受剪切应力而断裂, 使得硅电极和硅基底相互导通, 造成完全损伤。实验与仿真结果趋势一致, 误差较小, 相互验证。

In order to explore characteristics of CCD detector, according to the structural characteristics of CCD detectors, we developed a six-layer-structure, thermal-coupling, mathematical physical 3D model of a CCD detector that was irradiated by a 1.06 μm continuous laser. By changing the way of laser irradiating the CCD at different damage stages, the multi-layer damage mechanism of CCD detector was analyzed numerically and the time threshold was obtained. By comparison, the results demonstrated that due to melting the damage started from the microlens layer when the microlens focusing laser to photosensitive layer, causing the point damage of CCD. Then the aluminum film was fused and peeled by heat and stress after the microlens lost the ability to focus the beam, causing the vertical bright linear damage. With the molten Al film peeling off, the silicon electrode was irradiated directly and its surface was molted. Then the damaged wiring circuit made charges untransferable, causing the horizontal dark linear damage. Subsequently, the SiO2 insulating layer was torn up by shear stress, which made the molten silicon electrode in the upper and the silicon substrate in the lower conduct together, causing the complete damage of CCD. Additionally, the experimental and simulation results show the same trend with small error and verify each other.