Machining of optical freeform prisms by rotating tools turning

Slow slide servo machining is one of the most important approaches to cutting freeform prisms. However, it is not possible to cut the three freeform surfaces of a prism at one time since this causes a severe relative positioning error among the three surfaces. We propose a novel machining method called rotating tools turning (RTT) to machine the prism in one setting. Two different tools on the spindle are simultaneously employed for roughing and finishing respectively. The kinematics of the proposed method and the tool path strategy are analysed. The optimum system structure is obtained through an error model of alignment between the tool and workpiece. The proposed method is verified by experiments.