Ultra Precision Finishing of High NA Micro Aspherical Mold by Ultrasonic Vibration Assisted Polishing

Abstract

Demands for micro aspherical lenses are increasing in various optical devices and the micro glass lenses are generally molded by glass molding process with micro aspheric dies and moulds made of ceramic such as tungsten carbide. These dies and moulds are mostly ground with micro diamond wheels, but require additional finishing process as the NA of aspherical mould becomes higher and the required accuracy becomes higher. In this report, 4 axes (X,Y,Z,B) controlled polishing machine was developed and its polishing characteristics were tested with the tungsten carbide workpiece.