Design and control of precision work stage with air bearing for large size optical grating fabrication

Abstract

Scanning Beam Interference Lithography (SBIL) is an advanced large-diameter and high-precision plane grating manufacturing solution, which has very high requirements for the positioning accuracy and running speed of the work stage carrying the substrate. In order to improve the size and accuracy of optical grating manufacturing in scanning interference lithography further, air bearing with high precision, high loading capacity and high stiffness is one of the key components for the work stage. In this paper, in order to design a large stroke work stage which meets the demand, firstly, the air bearing, the core part of the work stage, is analyzed and calculated by finite element method, and the pressure distribution curve of the air bearing of the work stage is obtained. On this basis, the linear air bearing with high bearing capacity and high stiffness is designed by using the omni-directional preloading analysis method of high-precision motion platform. Based on the high-precision position feedback of grating encoder, the high-precision closed-loop control of 20nm (3σ) is realized by using PID control and trap filter, which meets the design and requirements, and provides technical and engineering support for the manufacture of large-scale optical grating.