Optics
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Abstract: The Diamond Light, Source beamline 112 (JEEP) is installing a monochromator for high-energy (50-150 keV) X-rays. It consists of two highly asymmetrically cut silicon crystals diffracting in the Laue case. These crystals will be bent to increase the bandpass to several hundred eV. It is necessary to estimate the tolerances for the angular alignment and the bending radii, and to account for gravitational and thermal distortions. A simple ray-tracing model has been developed for use with finite-element analyses. For simple cases, this model is backed by more precise wave-optical calculations.
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Jan 2008
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Optics
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Abstract: High brilliance, third generation synchrotrons, such as Diamond Light Source, the UK's national facility, are designed to produce intense beams of infra-red, ultra violet, and X-rays to benefit a wide variety of scientific investigations. In November 2009, 15 beamlines were operational and generating world-class academic and industrial research. By 2012, a further seven beamlines will be welcoming users. The successful scientific exploitation of the intense synchrotron light depends to a significant extent on the quality and performance of beamline optics. As synchrotron beamlines strive to produce micrometer-, and ultimately nanometer-sized focal spots, there is a pressing need for state-of-the-art optics, and the metrology instruments to accurately characterize them.
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Feb 2010
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Optics
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Abstract: X-ray compound refractive lenses (CRL) are becoming a widespread tool for the generation of microfocus spot sizes at synchrotron beamlines. The calculation of their performance by means of ray-tracing is useful for a rapid estimation of flux, resolution and focusing properties achievable in a beamline, when other optics are present, or simply to study the lens acceptance and focusing in the presence of a particular bending magnet, wiggler or undulator X-ray source. The ray-tracing method presented in this paper has been used to calculate the efficiency of beryllium CRL's using, for the instrument layout, realistic source size and divergence, and usual optics like perfect crystal monochromators. It is shown that the intensity transmitted by the lens, the effective aperture and the gain are in good agreement with analytical formulas. Additional information provided when running the program are the precise shape of beam at the focus, and at any position along the optical axis. For instance the intensity distribution at the CRL entrance and exit planes allows a comparison between the effective and the geometrical apertures. Finally, the method provides a precise value for the lens focal distance, which depends on the CRL length.
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Jul 2007
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Optics
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Abstract: In this work the results on X-ray micro-imaging by means of novel polycapillary optical elements will be presented. To simulate various radiation propagation processes in both single capillary and polycapillary systems, a PolyCAD code was developed. The new experimental results on radiation redistribution by novel capillary lenses in comparison with simulated data will be reported. The images of characterized extended samples (~ 3 mm) were recorded with 6 ?m resolution, the maximum provided by CCD. Polycapillary Optics CAD software X-ray tracing Imaging Confocal 02.60.Cb 02.70.-c 41.50. + h 42.15.-i 42.15.Dp 42.30.-d.
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Nov 2009
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Optics
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Abstract: Recently, many experiments have highlighted the advantage of using polycapillary optics for x-ray fluorescence studies. We have developed a special confocal scheme for micro x-ray fluorescence measurements that enables us to obtain not only elemental mapping of the sample but also simultaneously its own x-ray imaging. We have designed the prototype of a compact x-ray spectrometer characterized by a spatial resolution of less than 100??m for fluorescence and less than 10??m for imaging. A couple of polycapillary lenses in a confocal configuration together with a silicon drift detector allow elemental studies of extended samples (?3?mm) to be performed, while a CCD camera makes it possible to record an image of the same samples with 6??m spatial resolution, which is limited only by the pixel size of the camera. By inserting a compound refractive lens between the sample and the CCD camera, we hope to develop an x-ray microscope for more enlarged images of the samples under test.
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Dec 2008
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Optics
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Abstract: The Diamond-NOM is a non-contact, slope measuring profiler, capable of measuring surface topography of large optics (up to 1.5m long) with sub-nanometre height resolution and repeatability. On numerous occasions, the Diamond-NOM has proven to be an invaluable metrology tool for independently validating new beamline optics, and for investigating potential problems with optics from established beamlines. Data from the Diamond-NOM have consistently been in close agreement with results generated by a range of metrology instruments at other synchrotron laboratories and optic manufacturers. Prior to beamline installation, significant X-ray commissioning time was saved by optimizing and calibrating adaptive optics using the Diamond-NOM. We report on the current operational capabilities of the Diamond- NOM and give technical details of recent upgrades, including a penta-mirror (two, high grade reflectors used to mimic the internal working surfaces of a traditional pentaprism) and the capability to measure optics in sideward, downward, or upward facing geometries.
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Aug 2010
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Optics
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Abstract: A laser Fizeau interferometer system has been developed to characterize the figure error of large synchrotron X-ray mirrors using double-pass geometry. This opto-mechanical assembly comprises integrated rotation and translation stages to control: the output angle of the Fizeau interferometer; the surface normal of the optic under test; and the orientation of a high quality (?/100) retro-reflector. To negate the effects of gravitational deformations, the system can measure long optics (up to 1.5m in length) in the geometry (sideward, downward, or upward facing) in which they will ultimately be used on a synchrotron beamline. The system has been designed to minimize environmental noise and enable the measurement geometry to be changed quickly and safely. Compared to complementary techniques, including slope profilers such as the Diamond-NOM, surface height data from the Fizeau system can be obtained more rapidly (<1 minute). This makes the technique ideally suited to investigate the many degrees of freedom of adaptive optics, including piezo bimorph mirrors. The shape of such optics can also be monitored in real time to observe the dynamic effects of the surface in response to applied voltages. Results are presented to illustrate system performance, including repeatability levels. Calibration of the reference surfaces and the required environmental conditions are also discussed.
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Aug 2010
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Optics
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Abstract: Power Spectral Density (PSD) is an alternative method for specifying optical surfaces, and quantifies the contribution of each spatial regime to the total surface error. This approach naturally includes mid-range spatial frequency errors, which are often overlooked. The PSD method has recently been adopted by the Space and Astronomy industries, but has not yet received general acceptance within the synchrotron community. To assess the suitability for specifying synchrotron optics using PSD, Fast Fourier Transforms were performed on topography data from a range of optical surfaces of varying quality and manufacturing techniques. For each grade of optic, the entire regime (~100nm to ~50mm) of surface errors was measured, with overlapping bandwidths, using a micro-interferometer and a Fizeau interferometer. From this heuristic information, root-mean square "roughness" can be predicted over any desired spatial range, thus allowing direct comparison of metrology data obtained by instruments with different spatial bandwidths. We present an efficient approach for calculating 1-D and 2-D PSDs using MATLAB algorithms, and discuss analysis considerations, including "field of view" effects and instrument calibration.
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Aug 2010
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Optics
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Abstract: Modern synchrotron sources have provided for decades intense beams of photons over a large energy spectrum. The availability of improved optics and detectors has opened up new opportunities for the study of matter at the micrometre and nanometre scale in many disciplines. Whilst exploitation of micro-focused beams occurs almost daily in many beamlines, the production of beams of 100 nm is achieved on few instruments which use specialised optics. Refractive lenses, zone plates, curved mirrors, multilayers, and multilayer Laue lenses, can all focus x-rays to less than 50 nm under strict beam stability conditions. Focusing the synchrotron radiation to beam sizes smaller than 10 nm is considered the ultimate goal for the current decade. Silicon micro-technology has so far provided some of the most advanced x-ray refractive lenses; we report on design and characterisation of a novel silicon kinoform lens that is capable of delivering nano-beams with high efficiency
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May 2011
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Optics
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Abstract: The fourth international workshop on Adaptive and Active X-ray & XUV Optics (ACTOP11) was held on April 4-5, 2011, at Diamond Light Source in Oxfordshire, UK. This workshop follows on from earlier, successful active optic events at SOLEIL (2006), Elettra (2008), and Osaka (2009).
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Aug 2011
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