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The surface roughness on a diamond-turned AM aluminium (AlSi10Mg) mirror is presented which demonstrates the ability to achieve an average roughness of ~3.6nm root mean square (RMS) measured over a 3 x 3 grid. A Fourier transform of the roughness data is shown which deconvolves the roughness into contributions from the diamond-turning tooling and the AM build layers. In addition, two nickel phosphorus (NiP) coated AlSi10Mg AM mirrors are compared in terms of surface form error; one mirror has a generic sandwich lightweight design at 44% the mass of a solid equivalent, prior to coating and the second mirror was lightweighted further using the finite element analysis tool topology optimisation. The surface form error indicates an improvement in peak-to-valley (PV) from 323nm to 204nm and in RMS from 83nm to 31nm for the generic and optimised lightweighting respectively while demonstrating a weight reduction between the samples of 18%. The paper concludes with a discussion of the breadth of AM design that could be applied to mirror lightweighting in the future, in particular, topology optimisation, tessellating polyhedrons and Voronoi cells are presented.
The field of X-ray astronomy has been characterized by the development and launch of ever larger observatories with the culmination in the European Space Agency’s XMM-Newton and NASA's Chandra missions which are currently operational. XMM-Newton uses a multi-nested structure to provide modest angular resolution (∼10 arcsec) but large effective area, while Chandra sacrifices effective area to achieve the optical stability necessary to provide sub-arc second resolution. Currently the European Space Agency (ESA) is engaged in studies of the next generation of X-ray space observatories, with the aim of producing telescopes with increased sensitivity and resolution. To achieve these aims several telescopes have been proposed, for example ESA and NASA’s combined International X-ray Observatory (IXO), aimed at spectroscopy, and NASA’s Generation-X. In the field of X-ray astronomy sub 0.2 arcsecond resolution with high efficiency would be very exciting. Such resolution is unlikely to be achieved by anything other than an active system. The benefits of a such a high resolution would be important for a range of astrophysics subjects, for example the potential angular resolution offered by active X-ray optics could provide unprecedented structural imaging detail of the Solar Wind bowshock interaction of comets, planets and similar objects and auroral phenomena throughout the Solar system using an observing platform in low Earth orbit.
A major aim of the SXO project was to investigate the production of thin actively controlled grazing incident optics for the next generation of X-ray space telescopes. Currently telescope systems are limited in the resolution and sensitivity by the optical quality of the thin shell optics used. As part of its research programme an actively controlled prototype X-ray thin shell telescope optic of dimensions 30x10cm has been developed to bench test the technology. The design is based on thin nickel shells bonded to shaped piezo-electric unimorph actuators made from lead zirconate titanate (PZT).
The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be reproposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities.
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