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

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 calculated. 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 diamond grits and the beam waist radius are 0.89 J/cm² and 17.16 μm, respectively. Base on the optimization of laser parameters, a micro-structured surface with a size of 20 μm is able to generate on an electroplated diamond wheel with a grit size of 150 μm. 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.