Development of ultra-precision centering and leveling turntable using aerostatic bearing technology

To perform the ultra-precision centering and leveling operation of large surface under test in optical and mechanical precision measurements, a novel automatic centering and leveling turntable based on the aerostatic bearing technology is developed. In the functional module of centering, a planar aerostatic bearing and two micro-displacement actuators are utilized to achieve centering operation, and in the leveling functional module, a spherical aerostatic bearing, two microdisplacement actuators and a spring pivot are employed to realize the leveling operation. In the paper, the mathematical models of centering and leveling operation are obtained using coordinate transformation, and coupling between the centering and leveling operation is also analyzed. Furthermore, by using distance-measuring interferometer and autocollimator, the resolutions of centering and leveling operation are measured. Finally, errors of the centering and leveling operation are analyzed and the performance evaluation of the turntable is given. The experimental results show that, with 50Kg load, the leveling operation resolution is better than 1.2″; leveling operation range is ±1°; the centering operation resolution is better than 0.05μm; centering operation range is about ±5mm. The developed turntable can satisfy the requirements of ultra-precision, high resolution, wide range, frictionless, high load stiffness, stabilization and small driving force.