Design of a micro lapping system based on double-feedback control algorithm for manufacturing optical micro components

Abstract

This paper presents a micro lapping machine tool, which is dedicated for manufacturing the high-precision optical micro components with 3-D micro structures. And it can remove the damaged surface layer efficiently.In order to control machining process precisely, a double-feedback control system strategy is proposed and implemented. Lapping force signal from the clamp feeds back at the same time with position signal from grating scale close-looped devices. With the function of position keeping , a dual-stage drive micro-displacement servo system is used to provide the desired performance in the vertical feeding direction. Random lapping trace is formed with combinations of two mutually-perpendicular horizontal liner motion. A clamp with the function of micro force detection is designed to monitor the machining process and control the lapping force. Based on force feedback, a tool auto-checking strategy is conducted to realize the tool checking in limited tiny space. Corresponding experiments are undertaken to test the properties of the machine tool.And, the optical micro components are manufactured successfully. The optical components are measured and analysised before and after processing. The experimental results show that the position-keeping accuracy of the dual-stage feed drive system can reach to ±0.02μm, the resolution of motion control can reach to 20nm.The Sa value of the processed component can reach 0.0882um. Surface quality can be improved obviously and the damaged surface layer is removed efficiently.The theoretical and experimental results show the validity of the machine tool and the control algorithm.