Concept and modeling analysis of a high fidelity multimode deformable mirror

Abstract

Conventional deformable mirrors (DM) cannot meet the requirement of aberration controlling for advanced lithography tools. This paper illustrates an approach using the property that deformation of a thin plate is similar to optical modes to realize a high fidelity multimode deformable mirror whose deformation has characteristics of optical aberration modes. The way to arrange actuators is also examined. In this paper, a 36-actuator deformable mirror is taken as an example to generate low-order Zernike modes. The result shows that this DM generates the fourth fringe Zernike mode (Z4) defocus, and primary aberration Z5-Z8 with an error less than 0.5%, generates the fifth-order aberration Z10-Z14, and generates the seventh-order aberration Z17-Z20 with an error less than 1.1%. The high fidelity replication of the Zernike mode indicates that the DM satisfies the demand of controlling aberrations corresponding to the first 20 Zernike modes in an advanced lithography tool.