UCLA

In this article, a dual-stage positioning system for precisely tracking continuous scan and step scan profiles to meet the high-precision dynamic positioning requirements of space optical instruments is reported. A piezoelectric walking stage provides a long-stroke platform to which a short-stroke voice coil-actuated shuttle is mounted. The shuttle corrects for submicrometer deviations in the walking stage position and is designed with a low resonant frequency to passively reject disturbances produced by the walking stage. Both the walking stage and shuttle are instrumented with high-resolution interferometric encoders and a feedback system regulates the shuttle's position to achieve less than 7 nm RMS position error for constant velocity references of up to 0.5 mm/s. The shuttle is also capable of tracking step scan profiles with 10 ms settling times and 1.1 nm RMS position errors for steps up to 500 nm.