title: Figuring large optics at the sub-nanometer level: compensation for coating and gravity distortions.
abstract: Large, precision optics can now be manufactured with surface figures specified at the sub-nanometer level. However, coatings and gravity deform large optics, and there are limits to what can be corrected by clever compensation. Instead, deformations caused by stress from optical mounts and deposited coatings must be incorporated into the optical design. We demonstrate compensation of coating stress on a 370mm substrate to λ/200 by a process of coating and annealing. We also model the same process and identify the leading effects that must be anticipated in fabrication of optics for future gravitational wave detectors and other applications of large, precisely figured optics, and identify the limitations inherent in using coatings to compensate for these deformations.
authors.forename: Stephen
authors.initials: S
authors.lastname: Gensemer
authors.forename: Mark
authors.initials: M
authors.lastname: Gross