Active Microstructured Optical Arrays of Grazing Incidence Reflectors

Abstract

The UK Smart X-Ray Optics (SXO) programme is developing active/adaptive optics for terrestrial applications. One of the technologies proposed is microstructured optical arrays (MOAs), which focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels. Although such arrays are similar in concept to polycapillary and microchannel plate optics, they can be bent and adjusted using piezoelectric actuators providing control over the focusing and inherent aberrations. Custom configurations can be designed, using ray tracing and finite element analysis, for applications from sub-keV to several-keV X-rays, and the channels of appropriate aspect ratios can be made using deep silicon etching. An exemplar application will be in the microprobing of biological cells and tissue samples using TiKαradiation (4.5 keV) in studies related to radiation-induced cancers. This paper discusses the optical design, modelling, and manufacture of such optics.

Characterization of Micro-Structured Optical Arrays

“…Micro-structured optical arrays (MOAs) are currently in development by the UK Smart X-ray Optics consortium as x-ray focusing devices [1][2][3]. MOAs use grazing-incidence reflections from an array of channels all contributing to a focus spot, as shown in Fig.…”

“…1(b)) using piezoelectric actuators bonded to the surface, allowing control of the focal length of the MOA. In practice it is advantageous to use a pair of MOAs in series [3], either to produce 2-D focusing or to control aberrations.…”

Micromachining optical arrays

“…It consists of a tandem of two arrays, one being curved. The X-rays from the source are reflected twice at grazing incidence [4], first by the unbent array and then by the second array that is bent to a radius of curvature (4.7cm). The second array is curved by using piezoelectric actuation [5,6].…”