Tool Offset Flycutting Straight-Groove-Type Microstructures

Abstract

Optical microstructure arrays with regular geometry, like micro groove arrays, pyramid arrays, triangular pyramid arrays, etc., are commonly employed in optical components because of their distinctive special optical characteristics. Machining these microstructure arrays requires the collaboration of several linear axes of the ultra-precision machine tool (UPMT), but the machining ability of UPMT is constrained by the absence of some linear axes, such as the Y-axis. This study describes the development of a novel offset-tool-servo end flycutting (OTSEF) system integrating slow tool servo (STS) technology to fabricate microstructure arrays with straight-groove type using a UPMT with three axes (X-, Z-, and C-axis) configuration. This study developed a compensation mathematical model to linearize tool arc trajectory. After that, cutting experiments for micro groove arrays, pyramid arrays, and triangular pyramid arrays were performed by the machine tool and the machining quality was evaluated. Theoretical and experimental results demonstrate the high accuracy of these machined microstructure arrays with RMS (root mean square) error of less than 1 μm, which confirms the effectiveness of the proposed method to fabricate straight-groove type microstructure arrays only using three axes UPMTs. The proposed method not only offers a technological innovation for machining straight-groove-type microstructure arrays but also serves as a theoretical guide for more complex microstructure array machining.