Chen Lei, Kirchberg Stefan, Jiang Bing-Yan, Xie Lei, Jia Yun-Long, Sun Lei-Lei
Appl Opt. 2014 Nov 1;53(31):7369-80. doi: 10.1364/AO.53.007369.
A uniform plano-convex spherical microlens array with a long focal length was fabricated by combining the micromilling and injection molding processes in this work. This paper presents a quantitative study of the injection molding process parameters on the uniformity of the height of the microlenses. The variation of the injection process parameters, i.e., barrel temperature, mold temperature, injection speed, and packing pressure, was found to have a significant effect on the uniformity of the height of the microlenses, especially the barrel temperature. The filling-to-packing switchover point is also critical to the uniformity of the height of the microlenses. The optimal uniformity was achieved when the polymer melts completely filled the mold cavity, or even a little excessively filled the cavity, during the filling stage. In addition, due to the filling resistance, the practical filling-to-packing switchover point can vary with the change of the filling processing conditions and lead to a non-negligible effect on the uniformity of the height of the microlenses. Furthermore, the effect of injection speed on the uniformity of the height of the microlenses was analyzed in detail. The results indicated that the effect of injection speed on the uniformity of the height of the microlenses is mainly attributed to the two functions of injection speed: transferring the filling-to-packing switchover point and affecting the distribution of residual flow stress in the polymer melt.
在本工作中，通过结合微铣削和注塑成型工艺制备了具有长焦距的均匀平凸球面微透镜阵列。本文对注塑成型工艺参数对微透镜高度均匀性的影响进行了定量研究。发现注塑工艺参数的变化，即料筒温度、模具温度、注塑速度和保压压力，对微透镜高度的均匀性有显著影响，尤其是料筒温度。充模到保压切换点对微透镜高度的均匀性也至关重要。当聚合物熔体在充模阶段完全充满模腔，甚至稍微过度充满模腔时，可实现最佳的均匀性。此外，由于充模阻力，实际的充模到保压切换点会随充模工艺条件的变化而变化，并对微透镜高度的均匀性产生不可忽视的影响。此外，还详细分析了注塑速度对微透镜高度均匀性的影响。结果表明，注塑速度对微透镜高度均匀性的影响主要归因于注塑速度的两个作用：转移充模到保压切换点以及影响聚合物熔体中残余流动应力的分布。
