Actuation of Thin Glass for Grazing Incidence X-ray Mirrors

This thesis follows on from work done by the Smart X-ray Optics (SXO) consortium, which consisted of seven UK institutions working between 2007-2011 to produce advances in active x-ray optics. Although some final optical testing of a SXO prototype is described herein, most of the work is aimed towards exploring simpler prototypes which make use of commercially available components. We explore a new, scalable and low-cost method of actuating thin sections of glass within the context of grazing incidence mirrors for x-ray telescopes. Finite element analysis is used to simulate different arrangements of actuators and mountings, then commercially available macro-fibre lead zirconate titanate (PZT) actuators are attached to the rear surface of 0.4mm glass to produce a simple new prototype with a small number of degrees of freedom. Raytracing is used to evaluate the importance of different aberrations with respect to optical performance. Deflectometry is explored as a method for measuring surface height, and singular value decomposition is used to derive orthogonal influence functions and command matrices for the new prototype. We find that, although this technique shows some promise, there are important issues which would need to be overcome if it were to be scaled up to produce a working telescope. A full-sized x-ray telescope may have thousands of mirror segments which would need to be individually calibrated. A robust methodology does not yet exist for this process, but the large amount of hysteresis and variability exhibited by PZT actuators will surely make it harder. More work needs to be done in this area, but in the meantime this technology could be useful to create low-profile mirrors for other applications