Design and Fabrication of Microinjection Molded Miniature Freeform Alvarez Lenses

摘要

Microinjection molding is a mass production method used for affordable optical components. However, the intense nature of this process often results in part deformation and uneven refractive index distribution. These two factors limit the precision can be achieved in replicated optics. In order to understand the influences of injection molding to freeform optical devices, in this study, finite element method (FEM) was used to investigate the quality issues of the microinjection molded miniature Alvarez lenses. In addition, a metrology setup was proposed to evaluate the optical wavefront patterns in the molded lenses by using an interferometer based wavefront measurement system. This setup utilized an optical matching liquid to reduce the lens power such that the wavefront pattern with large deviation from the freeform lenses can be accommodated by a regular wavefront setup. The FEM simulation results were also used to explain the differences between the nominal and experimentally measured wavefront patterns of the injection molded Alvarez lenses.