Opt Express. 2021 Sep 27;29(20):32068-32080. doi: 10.1364/OE.438531.
This study aims to resolve the trade-off between the constraints and capabilities of ultra-precision machining to achieve ophthalmic Fresnel lenses. A general Fresnel lens pattern has a narrow variable pitch and curved grooves. However, we obviate the limitations of the tool nose radius constraint and the long tool path via ultra-precision machining of the modified Fresnel lens, ensuring a constant pitch of 0.1 mm and varying the height of straight grooves from 0 to 11 µm. Photorealistic raytracing visualization and MTF simulation verified the compatibility of the lens pattern with human perception sensitivity. Copper-coated mold was fabricated using a diamond tool with a tool nose radius of 5 µm. The replicated flexible Fresnel lens demonstrated a relative MTF imaging performance of 89.1% and was attached to the goggles for the qualitative assessment. The proposed Fresnel lens design and fabrication approach can be extended to applications in the visual and infrared ranges as well.
本研究旨在解决超精密加工在实现眼科菲涅尔透镜方面的约束和能力之间的权衡。一般的菲涅尔透镜图案具有狭窄的可变节距和弯曲的槽。然而，我们通过对修改后的菲涅尔透镜进行超精密加工来避免刀具鼻半径约束和长刀具路径的限制，从而确保节距为 0.1 毫米且直槽的高度从 0 到 11 µm 变化。逼真的光线追踪可视化和 MTF 模拟验证了透镜图案与人眼感知灵敏度的兼容性。使用刀具鼻半径为 5 µm 的金刚石刀具制造了镀铜模具。复制的柔性菲涅尔透镜表现出相对 MTF 成像性能为 89.1%，并安装在护目镜上进行定性评估。所提出的菲涅尔透镜设计和制造方法可以扩展到视觉和红外波段的应用中。
