Design of a Closed-Loop Feedback System for testing and Prototyping New Deformable Mirror Technologies

Abstract

The objective of this Senior Thesis is to assess the capabilities of a new type of ferrofluid deformable mirror (ferro-DM) which utilizes 7 inductive actuators and a cellulose pellicle facesheet. To do this, a new testbed was designed and assembled in order to provide accurate measurements of the wavefront from the mirror in two different orientations, horizontal and vertical. The system is composed of a light source, a wavefront sensor, and a ferrofluid deformable mirror. Collimated light is reflected off the ferro-DM, providing a modified wavefront which can then be measured using the wavefront sensor. By actuating the 7 inductors within the ferro-DM, the facesheet can be deformed in different ways to introduce various wavefront shapes to the original light beam. The addition of a facesheet allows us to actuate the mirror surface using pressure control as well. Thus, both modes of actuation were explored to determine their feasibility as well as to help guide future ferro-DM designs. The ferro-DM used in this thesis was conceptualized by Dr. Tyler Groff, in Professor Jeremy Kasdin’s High Contrast Imaging Laboratory. The idea behind this type of DM is to use the magnetic properties of ferrofluid to deform the reflective surface as desired. Proving that such a mirror can be manufactured and controlled would provide a new tool to field of adaptive optics systems.