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Proceedings Paper

Microstructured optical arrays for smart x-ray optics
Author(s): Camelia Dunare; William Parkes; Tom Stevenson; Alan Michette; Slawka Pfauntsch; Shahin Sahraei; Matthew Shand; Dou Zhang; Daniel Rodriguez Sanmartin; Tim Button; Charlotte Feldman; Richard Willingale; Peter Doel; Hongchang Wang; Ady James
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Paper Abstract

The Smart X-ray Optics (SXO) programme is developing advanced active-adaptive optics for X-rays. There are two main themes: large optics for applications in astronomy and small scale optics for micro-probing of biological cells and tissue samples using Ti or Cr Kα radiation (4.5keV and 5.4keV, respectively) in studies related to radiation induced cancers. For the latter objective, microstructured optical arrays (MOAs) have been proposed. These consist of an array of channels deep etched in silicon. They use grazing incidence reflection to focus the X-rays through consecutive aligned arrays of channels, ideally reflecting once off a channel wall in each array. Bending the arrays allows variable focal length. The adaptivity is achieved by flexing the arrays using PZT (Lead Zirconate Titanate)-based piezo actuators. The array bending has been modelled using finite element analysis (FEA) and the results showed that for reasonable efficiency, the wall roughness of the channels should not exceed 2nm. This paper describes two techniques of fabrication the MOAs: dry etching and wet etching. The first method requires a special equipment called "inductively coupled plasma" (ICP) using Bosch processes that are designed to produce features with a high aspect ratio with vertical walls. The second method involves using an alkaline solution for etching <110> silicon wafers. This type of wafer was selected because of the large wet etch ratio between the (111) and (100) planes that leads to smooth vertical walls. For our application tetra-methyl-ammonium hydroxide (TMAH) was used as it is fully compatible with CMOS integrated circuit processes.

Paper Details

Date Published: 30 April 2009
PDF: 12 pages
Proc. SPIE 7360, EUV and X-Ray Optics: Synergy between Laboratory and Space, 736015 (30 April 2009); doi: 10.1117/12.820598
Show Author Affiliations
Camelia Dunare, Univ. of Edinburgh (United Kingdom)
William Parkes, Univ. of Edinburgh (United Kingdom)
Tom Stevenson, Univ. of Edinburgh (United Kingdom)
Alan Michette, King's College London (United Kingdom)
Slawka Pfauntsch, King's College London (United Kingdom)
Shahin Sahraei, King's College London (United Kingdom)
Matthew Shand, King's College London (United Kingdom)
Dou Zhang, Univ. of Birmingham (United Kingdom)
Daniel Rodriguez Sanmartin, Univ. of Birmingham (United Kingdom)
Tim Button, Univ. of Birmingham (United Kingdom)
Charlotte Feldman, Univ. of Leicester (United Kingdom)
Richard Willingale, Univ. of Leicester (United Kingdom)
Peter Doel, Univ. College London (United Kingdom)
Hongchang Wang, Univ. College London (United Kingdom)
Ady James, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 7360:
EUV and X-Ray Optics: Synergy between Laboratory and Space
René Hudec; Ladislav Pina, Editor(s)

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