Flexible fabrication of Fresnel micro-lens array by off-spindle-axis diamond turning and precision glass molding
Flexible fabrication of Fresnel micro-lens array by off-spindle-axis diamond turning and precision glass molding
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DOI：
10.1016/j.precisioneng.2021.11.013
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发表时间：
2021-11-25
影响因子：
3.6
通讯作者：
Yan, Jiwang
中科院分区：
文献类型：
--
作者：
Zhang, Lin;Yi, Allen Y.;Yan, Jiwang
菲涅耳微透镜阵列具有近波长特性，在光学系统的最小化方面具有显著的优势。然而，在传统的金刚石车削加工菲涅耳微透镜阵列时，由于表面轮廓的不连续特性，导致刀具侧面与加工表面之间存在干涉。本文提出了一种新型的离轴金刚石车削加工菲涅耳微透镜阵列插模的方法，并开发了一种刀具轨迹生成算法。每个透镜的生成被视为一个独立的转动操作，整个菲涅耳微透镜阵列的制作是由一系列重复的转动操作完成的。该方法避免了刀具与被加工表面的干涉，提高了每个透镜的形状精度和表面完整性。然后，将菲涅耳微透镜阵列嵌模进一步用于精密玻璃成型，将微透镜结构复制到透明聚合物基板上。实验结果表明，金刚石旋转和模压菲涅耳微透镜阵列均能获得均匀的质量。作为应用，介绍了一种基于模制菲涅耳微透镜阵列的小型成像系统。本文提出的加工方法可用于菲涅耳微透镜阵列和其他非连续轮廓微光学器件的加工，具有较高的加工精度和加工效率。
Fresnel micro-lens arrays with close-to-wavelength features have significant advantages in minimization of optical systems. However, in the fabrication of a Fresnel micro-lens array by conventional diamond turning, the discontinuous features of the surface profile cause interference between the tool flank face and the finished surface. In this manuscript, a novel off-spindle-axis diamond turning method is proposed to fabricate Fresnel micro-lens array mold insert and a toolpath generation algorithm is developed. The generation of each lenslet is treated as an independent turning operation, and the whole fabrication of a Fresnel micro-lens array is completed by a succession of repetitive turning operations. With this approach, the interference between the tool and the finished surface is avoided, and the form accuracy and surface integrity are improved for each lenslet. Then, the Fresnel micro-lens array mold insert is further utilized in precision glass molding to replicate the micro-lens structures onto transparent polymer substrates. The experimental results indicate that both the diamondturned and molded Fresnel micro-lens arrays are achieved with homogeneous quality. As an application, a compact imaging system based on the molded Fresnel micro-lens array is demonstrated. The proposed machining method in this study can be employed in the fabrication of Fresnel micro-lens arrays and other micro-optics with discontinuous profiles with high accuracy and machining efficiency.