Large-aperture deformable mirror correction of tiled-grating wavefront error

Abstract

\nWhen tiling three gratings, with each individually\nexhibiting astigmatism and power due to holographic errors and coating\nstress, the resulting wavefront aberrations contain high-frequency\ncomponents as well as the fundamental frequency, which is nearly three\ncycles across the aperture in the tiling direction. A deformable mirror (DM)\nthat was designed to compensate for much slower errors (e.g., those arising\nfrom distortion in amplifier disks) is being used to compensate for this\ntiling-induced error. This investigation studies the effectiveness of\ncompensating only the fundamental frequency of the tiled aberration, and\nshows that this provides a significant improvement that is adequate for a\nrange of expected aberrations. Limitations of the DM correction technique\nare also studied.\n