Cost effective deformable mirror technology for astronomy applications

Abstract

This thesis presents work undertaken by the author in the course of studies for an Engineering Doctorate at the School of Engineering and Physical Sciences of Heriot Watt University, and the United Kingdom Astronomy Technology Centre. The motivation for the work is to make adaptive optics more accessible to astronomy applications where cost has been a factor. At present the complexity and cost of a principal component of adaptive optic systems, the deformable mirror (DM), has limited its adoption in instrumentation and industrial applications. Novel contributions to the general body of knowledge include: a) The development of an integrated multi-layer PZT 196 actuators array on a 1.2 mm pitch. The array is constructed from 85 layers, each 20 µm thick giving an extension of 2 µm for an applied voltage of 80 Volts. b) The development of electronics for a low cost, array addressable, actuator drive which facilitates a parametric comparison of actuator permittivity to actuator extension. A 5% resolution of actuator extension was achieved with small extension loss of 62.5 picometers/second at refresh rate of up to 500 Hz. c) Reliable zeolite loaded epoxy bonding of the deformable mirror surface to the actuator array through the introduction of 1 µm groves in the side walls of the mirror support legs. Bond strength of 4.1 MPa was achieved which is greater than the 1.2 MPa required. This thesis opens the prospect of the construction of actuator staves leading to an increase the versatility of array construction. The advantages identified include reductions of the complexity of forming additional electrodes and of tolerance on actuator dicing to form individual actuators in the array. Solutions have been identified towards a future prototype deformable mirror with integrated electronic actuator drive and extension sensing.