Progress on the development of active micro-structured optical arrays for X-ray optics

The Smart X-Ray Optics (SXO) project comprises a U.K.-based consortium developing active/adaptive micro-structured optical arrays (MOAs). These devices are designed to focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels etched in silicon. The silicon channels have been produced both by dry and wet etching, the latter providing smoother channel walls. Adaptability is achieved using piezoelectric actuators, which bend the device and therefore change its focal distance. We aim to achieve a 5 cm radius of curvature which can provide a suitable focal length using a tandem pair MOA configuration. Finite Element Analysis (FEA) modelling has been carried out for the optimization of the MOA device design, consider different types of actuators (unimorph, bimorph and active fibre composites), and different Si/piezoelectric absolute and relative thicknesses. Prototype devices have been manufactured using a Viscous Plastic Processing Process for the piezoelectric actuators and dry etched silicon channels, bonded together using a low shrinkage adhesive. Characterisation techniques have been developed in order to evaluate the device performance in terms of the bending of the MOA channels produced by the actuators. This paper evaluates the progress to date on the actuation of the MOAs, comparing FEA modelling with the results obtained for different prototype structures.