Development of micro polishing system using a magnetostrictive vibrating polisher

Recently, micro-optical lenses are highly required in new fields such as Fresnel lenses for solar panels and Wafer Level Cameras (WLC). The lenses are generally molded by micro ceramic molds. In this paper, a novel vibration-assisted polishing (VAP) method by using a magnetostrictive vibrating polisher is proposed to improve the efficiency and stability of micro-optical mold polishing. The magnetostrictive vibrating polisher is composed of a vibrator and a small polishing tool. The small polishing tool is screwed into the head of the vibrator. The vibrating polisher is fixed on a 5-axis (X, Y, Z, B, C) controlled table via a balancing adjustment mechanism. The vibration characteristics are evaluated and the polisher vibrates in a lateral motion at frequency of 9.2 kHz with amplitude of 30 μm. The polishing force is controllable within a range of 2–200 mN with a resolution of 2 mN by the balancing adjustment mechanism. Some fundamental polishing experiments are conducted by using molds made of binderless tungsten carbide; the shape of removal function is acquired and surface roughness is improved from 30 nm Rz (4 nm Ra) to 10 nm Rz (2 nm Ra).