光学玻璃的激光微结构化砂轮精密磨削

Precision grinding of optical glasses by laser micro-structured grinding wheels

为了降低大磨粒金刚石砂轮磨削光学玻璃时的亚表层损伤,利用纳秒脉冲激光对金刚石砂轮进行了表面微结构化加工,并采用该砂轮研究了光学玻璃的精密磨削加工。首先,计算了金刚石磨粒在纳秒脉冲激光辐射下的烧蚀阈值和激光束腰半径;然后,分析了纳秒脉冲激光在金刚石磨粒上加工的微结构形貌以及微结构化过程中的热损伤;最后,采用微结构化大磨粒金刚石砂轮进行光学玻璃的磨削实验,并分析了亚表层的损伤情况。实验结果表明:金刚石磨粒在纳秒脉冲激光辐射下的烧蚀阈值为0.89J/cm,激光束腰半径为17.16μm。在粒度为150μm的大磨粒电镀金刚石砂轮上可以实现结构尺寸为20μm的微结构表面加工。与传统金刚石砂轮相比,微结构化砂轮磨削后的光学玻璃亚表层损伤深度降低了40%,达到了降低光学玻璃磨削亚表层损伤的目的。

To reduce the subsurface damage of optical glasses induced by a coarse-grained diamond wheel, the diamond wheel surface was processed in a micro-structuring mode by a nanosecond pulse laser. The grinding wheel was used to investigate the grinding performance of optical glasses. First, the ablation threshold of diamond grits under a ns laser pulse and the laser beam waist radius were cal- culated. And then, the ablation morphological characteristics were explored, and the thermal damage of diamond grits was analyzed. Finally, the optical glass grinding experiments were performed and the subsurface damage was analyzed. The experimental results show that the ablation threshold of dia- mond grits and the beam waist radius are 0.89 J/cm^2 and 17.16μm, respectively. Base on the optimi-zation of laser parameters, a micro-structured surface with a size of 20 μm is able to generate on an e- lectroplated diamond wheel with a grit size of 150μm. As compared with a conventional diamond wheel, the subsurface damage depth of optical glass workpiece induced by micro-structured diamond wheel is reduced by 40% and realizes the decrease of subsurface damage in optical glass precision grinding.