Cross-coupling effect of large range XY nanopositioning stage fabricated by stereolithography process

This paper presents cross-coupling effect of a polymer-based large range XY nanopositioner fabricated by an additive manufacturing (AM) process, stereolithography. The flexural properties were preliminary characterized to design the XY stage capable of ±1.0 mm range motion. The voice coil motors were aligned along the moving axes of the stage, and optical knife edge displacement sensors were placed at the center of the stage without Z-axis offset distance perpendicular to the moving axes to mitigate Abbe error and minimize cosine error. The cross-coupling of AM stage was 3.4% and 8.1% for XY and YX axes that is relatively larger than the value 1.0% estimated by the finite element method. It was considered to be responsible for AM fabrication tolerance or local irregularity in material properties because those properties are highly dependent on curing temperature and time even though the stage is fabricated layer-by-layer under the identical condition. The AM stage thus should be positioning feedback-controlled to avoid cross-coupling effect. As a result, the root-mean-square radial trajectory error was 3.62 μm under radius 1.0 mm and 1 Hz circular motion condition. These results indicated that the AM stages can be used for large range nanoprecision applications such as scanning, lithography, or fiber-optics alignments.