APPLICATION OF PRECISION ENGINEERING FOR NANOMETRE FOCUSSING OF HARD X- RAYS IN SYNCHROTRON BEAM LINES A thesis submitted for the degree of Master of Philosophy by Stewart Mark Scott Department of Advanced Manufacturing and Enterprise Engineering Brunel University November 2011 Corrections Corrections Issue No Date 1st Draft 8 September 2011 2nd Draft 31 October 2011 Issued for examination 29 November 2011 Viva comments incorporated 7 February 2012 ii Abstract Abstract Many modern synchrotron beamlines are able to focus X-rays to a few microns in size. Although the technology to achieve this is well established, performing routine experiments with such beams is still time consuming and requires careful set up. Furthermore there is a need to be able to carry out experiments using hard X-ray beams with even smaller beams of between 100nm and 10nm. There are focussing optics that are able to do this but integrating these optics into a stable and a usable experimental set up are challenging. Experiments can often take some hours and any change in position of the beam on the sample will adversely affect the quality of the results. Experiments will often require scanning of the beam across the sample and so mechanisms suitable for high resolution but stable scanning are required. Performing routine experiments with nanometre sized beams requires mechanical systems to be able to position the sample, focussing optics, detectors and diagnostics with significantly higher levels of stability and motion resolution than is required from so called micro focus beam lines. This dissertation critically reviews precision engineering and associated technologies that are relevant for building nano focus beamlines, and the following key issues are explored: Long term position stability due to thermal effects Short term position stability due to vibration Position motion with nanometre incremental motion Results of some tests are presented and recommendations given. Some test results are presented and guidance on designing nano focus beamlines presented. iii Acknowledgements Acknowledgements The Author would like to thank the support of Prof Kai Cheng of Brunel University and Dr Andy Dent, Mr Jim Kay and Dr Kawal Sawhney of Diamond Light Source Ltd in carrying out this work. I also thank Diamond Light Source for the funding and use of equipment. All diagrams and images are the authors unless stated. iv Table of contents Table of Contents Chapter 1. Introduction ................................................................................................ 1 1.1 Synchrotrons ...................................................................................................... 1 1.1.1 History ......................................................................................................... 1 1.1.2 How synchrotrons work .............................................................................. 1 1.2 Diamond Light source ......................................................................................... 2 1.3 Hard X- ray applications ..................................................................................... 3 1.4 Requirements for nanometre precision mechanics ........................................... 4 1.5 Aims and Objectives ........................................................................................... 4 1.6 Scope of the dissertation .................................................................................... 5 1.6.1 Specification ................................................................................................ 5 1.6.2 To determine what are the technical problems to be addressed .............. 5 1.6.3 To highlight what are the current technologies ......................................... 5 1.6.4 To review trends in current research .......................................................... 5 1.6.5 To carry out some test and development ................................................... 6 1.6.6 To make recommendations in any changes of design methodology or technology that Diamond Light Source should adopt in the future.......................... 6 Chapter 2. Scientific requirements and challenges ..................................................... 7 2.1 Science at the nanometre scale. ........................................................................ 7 2.2 Nano beamlines .................................................................................................. 7 2.2.1 APS............................................................................................................... 7 2.2.2 Soleil ............................................................................................................ 7 2.2.3 ESRF ............................................................................................................. 8 2.2.4 NSLSII ........................................................................................................... 9 2.2.5 PETRA III ...................................................................................................... 9 2.2.6 Spring 8 ........................................................................................................ 9 2.2.7 ANKA ......................................................................................................... 10 v Table of contents 2.2.8 Diamond .................................................................................................... 10 2.3 Focussing optics ............................................................................................... 10 2.3.1 Kirkpatrick-Baez mirrors ........................................................................... 10 2.3.2 Refractive lenses ....................................................................................... 12 2.3.3 Fresnel Zone plates ................................................................................... 15 2.3.4 Multi layer laue lenses .............................................................................. 16 2.3.5 Capillary tubes ........................................................................................... 16 2.3.6 Waveguides ............................................................................................... 17 2.3.7 Diffraction limit ......................................................................................... 18 2.3.8 Summary of focussing optics .................................................................... 18 2.4 Types of experiments suitable for nano focus ................................................. 19 2.4.1 Nano diffraction ........................................................................................ 19 2.4.2 Micro fluorescence ................................................................................... 19 2.4.3 Transmisive imaging .................................................................................. 21 2.4.4 Phase contrast imaging ............................................................................. 22 2.5 Technical challenges for a sub 100nm beam experiment station ................... 22 2.5.1 Focussing distance .................................................................................... 22 2.5.2 Positional stability ..................................................................................... 23 2.5.3 Sample alignment ..................................................................................... 23 2.5.4 Sample scanning ....................................................................................... 24 2.5.5 User sample mounting .............................................................................. 25 2.5.6 Detector integration ................................................................................. 25 2.5.7 Alignment and diagnostics ........................................................................ 25 2.5.8 Sample mounting and sample changing ................................................... 27 2.5.9 Integration into existing beamlines .......................................................... 30 Chapter 3. Thermal stability ....................................................................................... 32 3.1 Thermal stability issues .................................................................................... 32 3.2 Low thermal expansion materials .................................................................... 32 3.2.1 Glass ceramics ........................................................................................... 32 3.2.2 Sialon ......................................................................................................... 34 3.2.3 36% Nickel iron alloys ............................................................................... 35 vi Table of contents 3.2.4 Metal matrix composites .......................................................................... 36 3.2.5 Carbon fibre composites ........................................................................... 38 3.2.6 Silicon carbide ........................................................................................... 40 3.2.7 Nexcera ..................................................................................................... 42 3.2.8 Ceramic composites .................................................................................. 43 3.2.9 Granite....................................................................................................... 43 3.2.10 Titanium ...................................................................................................