Development of ultraprecise positioning X–Y stage composed of pneumatic servo bearing actuators

A prototype X–Y stage for ultraprecise positioning composed of six pneumatic servo bearing actuators was proposed and developed. First, the basic performance of the pneumatic servo bearing actuator with a spherical aerostatic bearing was investigated before assembling it to the X–Y stage. In the actuator, pressurized air controlled by a servo valve moves an actuated spool ultraprecisely. Even under open-loop control, the actuator provided accurate replication and positioning resolution on a nanometer order. Second, the specifications of the constructed X–Y stage were evaluated, especially focusing on its minimum resolution. The minimum positioning resolution of the X–Y stage was 3 nm under the best conditions, and the positioning resolution as a practical specification was approximately 10 nm for all conditions, even without feedback controls.