Active X-ray optics for the next generation of X-ray space telescopes.
Doctoral thesis, UCL (University College London).
Described within is the design, manufacture, metrology and X-ray testing of an active X-ray prototype intended for the next generation of X-ray telescopes. One of the challenges faced by the X-ray telescope community is how to combine high resolution and high sensitivity into one system, as weight limitations place constraints on the optics that can be launched. Therefore the mandate of the active X-ray prototype is to provide high sensitivity through the ability of the optics to be nested and to deliver high angular resolution through the active control of the optic’s form. Piezoelectric unimorph actuators provide the active component: it is intended that they will correct for figure errors within the optic and therefore increase the angular resolution capability. The prototype’s design is based upon an ellipsoidal segment which provides point-to-point focussing of an X-ray source. The prototype itself is composed of an electroformed nickel optic where the non-reflective surface is populated with 30 piezoelectric actuators and it is the production of the prototype that is the core of the presented research. Metrology of the actuators’ influence functions is presented and highlight the prototype’s ability to deform its optic surface by microns. In addition, the measured influence functions are compared against finite element models and a distinct similarity between the functions is observed. The prototype was tested at an X-ray beamline facility in November 2008 and the results showed the prototype’s ability to correct the optic to achieve an improved angular resolution: from 0.786 arc-minutes to 0.686 arc-minutes in terms of full width half maximum. Finally, difficulties in the manufacture of the prototype and X-ray testing shall be presented alongside future work in conclusion to this thesis.
|Title:||Active X-ray optics for the next generation of X-ray space telescopes|
|Open access status:||An open access version is available from UCL Discovery|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy|
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