Fabrication of Micro Infrared Fresnel Lens Arrays by Virtual Spindle Based Tool Servo Diamond Turning and Precision Glass Molding

摘要

Chalcogenide glasses are emerging as low-cost alternatives for infrared applications. These materials have promising characteristics that can improve both manufacturing processes and device performance. In this research, we aim to develop a novel manufacturing approach utilizing virtual spindle based tool servo diamond turning and precision glass molding to fabricate micro infrared Fresnel lens arrays in large-volume at low-cost. This novel diamond turning approach can realize rotation-axis transition to any specified position by combining multiple translational and rotational servo motions of the precision machine. During diamond turning, the discontinuous features of the Fresnel lens can be generated by transferring the rotation-axis from one local center to another. After the mold is diamond machined, molding is conducted on a commercial precision molding machine with optimized processing parameters. After the molded element is released, the profile of the replicated infrared element is measured using an interferometer. The results closely match the dimensions of the curvature of the lenslets on the mold. An experimental setup utilizing molded microlenses is used to validate the optical performance of the molded microlenses. This study demonstrates the feasibility of the proposed manufacturing process for improved fabrication efficiency of infrared elements and allows low-cost high-precision infrared micro-optics to be produced in high volume.