Adaptive Optics Control Using Transverse Actuators
Institution: Sharif University of Technology
Type: MSc thesis
Problem
Large telescopes use deformable mirrors to correct atmospheric distortions in real time. The mirror surface must be shaped precisely by an array of actuators. The inverse problem, determining what actuator inputs produce a desired mirror shape, is mathematically ill-posed, especially for transverse (in-plane) actuators that deform the mirror through bending rather than direct displacement.
What Was Novel
Most adaptive optics systems use normal (out-of-plane) actuators that push the mirror surface directly. Transverse actuators are mechanically simpler and more compact, but the relationship between actuator input and surface shape is governed by a PDE (plate bending equation), making the inverse problem significantly harder.
I formulated this as a PDE-constrained optimization problem and developed a control algorithm that solves the inverse dynamics in real time. The approach handles the non-trivial coupling between transverse actuator forces and the resulting surface deformation, which previous methods either ignored or approximated crudely.
Impact
Demonstrated that transverse actuators can achieve comparable shape control accuracy to normal actuators, opening a path to more compact and mechanically robust adaptive optics designs for astronomical telescopes.