Nanometer positioning and its micro-dynamics

A one-axis mechanism, driven by an AC linear motor and guided by a rolling ball guide, has been constructed. The micro-dynamics of the rolling guide shows that the group of balls of the guide behaves as a rigid spring within a displacement of about 100 nm, and normal rollings take place for a displacement greater than 100 mu m. These different characteristics are used to control the stage during coarse and fine positioning. A coarse positioning with 100 nm resolution, 200 mm s^-1 maximum velocity and 250 mm stroke, and a fine positioning with better than 1 nm resolution without backlash are achieved. The switching from the coarse positioning to the fine positioning is studied.