Active optics theory: compensation of aberration using the single actuator principle

Abstract

Active Optics allows the possibility of using the generation of complex variable optical surfaces to keep the optical layout of future instruments relatively simple, something which could be of great interest to future telescopes such as E-Elt, Tmt. The aim of this article is to describe the development of the "single actuator - single mode" principle that makes it possible to generate single optical modes on a circular mirror using a single actuator at a specific location. We show the progress from design analysis (elasticity theory, finite element analysis etc) through to experimental validation for Variable Curvature Mirrors and Variable Astigmatism Mirrors. Current and future applications of these active mirrors are discussed in the framework of the EAGLE instrument for E-Elt and we present plans for further development of the technique.