Long-Range Nano-Scanning Devices Based on Optical Sensing Technology

Abstract

A compact, low-cost, and high-performance nanopositioning system for dimensional metrology tools. A polymer-based large-range nanopositioning system was fabricated by an additive manufacturing (AM) process, stereolithography. The AM flexural properties were characterized to design the nanopositioning stage capable of millimeter range motion. 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. Also, a design principle of an optical knife-edge sensor (OKES) is to provide a long range and high accuracy for nanopositioning. The OKES utilizes interference fringe due to optical knife-edge diffraction and has more than 40 % of high sensor sensitivity slope. The OKES was modeled by using electromagnetic wave propagation principle and experimentally verified by testing the OKES with the XY stage. The sensor noise level shows X 20.1 nm and Y 19.4 nm, and the fundamental sensing limit of the OKES was estimated X 0.19 nm/\( \sqrt{\mathrm{Hz}} \) and Y 0.23 nm/\( \sqrt{\mathrm{Hz}} \) for ±1.0 mm working range. In the XY circular motion, 0.2/1.0/2.0 mm diameter at 1 Hz, the trajectory root-mean-square errors were 0.77/2.50/3.50 μm, respectively. These results indicate that the OKES can be a good alternative to precision metrology tools in terms of large working range, positioning accuracy, resolution, linearity, bandwidth, and control effectiveness.