There is growing interest at synchrotron light and X-ray free electron laser facilities to explore and improve the dynamic performance of piezoelectric bimorph deformable X-ray mirrors. Many beamlines, especially those dedicated to Macromolecular Crystallography, need to measure hundreds of samples per day. Shorter acquisition time requires rapid changes in the focus of the X-ray beam to condense the maximum photon density onto the sample. This is necessary to match the X-ray beam to the dimensions of the sample, or to probe variable sized regions of larger samples. Fine control of the X-ray beam becomes crucial for ensuring the highest quality of scientific data and increased throughput. Previous work at Diamond Light Source successfully changed the X-ray beam focus and stabilised it in under 10 seconds using piezoelectric bimorph deformable mirrors. Further updates to the controls software of the programmable HV-ADAPTOS high-voltage power supply (from CAEN / S.RI. Tech) now make it possible to control individual electrodes at 1 Hz using custom voltage profiles. This allows localized compensation of piezo creep, thus improving X-ray beam shape, significantly reducing stabilisation time, and eliminating curvature drift. For ex-situ validation, dynamic changes in the surface of the bimorph mirror need to monitored in real-time with sufficient spatial sensitivity. In this paper, we show that the active optical surface of a bimorph mirror (from Thales-SESO) can be accurately changed with sub-nanometre height sensitivity by dynamically monitoring the mirror’s surface using an array of high-speed (up to 200 kHz) Zygo ZPS™ absolute interferometric displacement sensors mounted in an independent metrology frame.
In this work we present the application of a 2D single grating wavefront sensor to align and characterize the 100 nm focus at the Coherent X-ray Imaging (CXI) endstation at the Linac Coherent Light Source (LCLS). The results agree well with a model of the system, indicating that the mirrors perform as designed when alignment is optimized. In addition, a comparison with the imprint technique confirms the validity of the results, which showed that wavefront-based alignment resulted in negligible astigmatism. Analysis of the retrieved focus profile indicates that intensities <1021 W=cm2 are achievable with currently available LCLS beam parameters and optimal mirror alignment.
The SQS scientific instrument at the European XFEL is dedicated to investigations in the soft X-rays regime,
in particular to studies of non-linear and ultrafast processes in atoms, molecules and clusters using a variety of
spectroscopic techniques. It will be equipped with a Kirkpatrick-Baez (KB) adaptive mirror system enabling
submicron focusing and access to variable focal distances. In this paper we describe the conceptual design of the
beam transport and focusing layout based on the KB system. The design includes a study of feasibility based
on the comparison between the required source and image positions and the theoretical limits for the accessible
mirror profiles.
The design and implementation of a pair of 100 mm-long grazing-incidence total-reflection mirrors for the hard
X-ray beamline Nanoscopium at Synchrotron Soleil is presented. A vertically and horizontally nanofocusing
mirror pair, oriented in Kirkpatrick-Baez geometry, has been designed and fabricated with the aim of creating a
diffraction-limited high-intensity 5 − 20 keV beam with a focal spot size as small as 50 nm. We describe the design
considerations, including wave-optical calculations of figures-of-merit that are relevant for spectromicroscopy,
such as the focal spot size, depth of field and integrated intensity. The mechanical positioning tolerance in the
pitch angle that is required to avoid introducing high-intensity features in the neighborhood of the focal spot
is demonstrated with simulations to be of the order of microradians, becoming tighter for shorter focal lengths
and therefore directly affecting all nanoprobe mirror systems. Metrology results for the completed mirrors are
presented, showing that better than 1.5 °A-rms figure error has been achieved over the full mirror lengths with
respect to the designed elliptical surfaces, with less than 60 nrad-rms slope errors.
We present the design, fabrication and characterization of a novel adaptive X-ray optic by bringing together bimorph
adaptive technology and the novel Elastic Emission Machining "super-polishing" technique. This super-polished
adaptive mirror provides variable focal distance and local figure control in the sub-nm range. The optic has the potential
to generate distortion-free beams, and enable wavefront control.
X-ray studies of materials in extreme conditions of pressure call for focusing optics able to deliver very clean micron-size focal spots of high energy X-rays with added stringent requirements of flexibility to accommodate different experimental geometries and fast focal spot size adjustment. These requirements are fully met by multi-electrode modular piezoelectric bimorph mirrors (PBMs) in Kirkpatrick-Baez configurations, and these optical systems have already been successfully used for several years at high brilliance 3rd generation synchrotron radiation facilities such as the ESRF and SPring-8. The optical characterization and in-situ X-ray performance of the first pair of modular PBMs installed at the Advanced Photon Source at
Argonne national laboratory is reported here. Metrology tests show that the mirrors are able to approximate an arbitrary surface described by a 9th order polynomial in shape with only 100 Å rms shape error over their full optical surface. Full adaptive zonal control allows wave front correction, delivers optimum focal spot profiles (as small as 8.5 (H) x 5.0 (V) μm2 FWHM at a focal distance of 1 m) and fully achieves the creep-free short and long term stability and repeatability required by the experimental program.
This paper reports on the performances of a test prototype mirror, based on the Piezoelectroic Bimorph Mirror technology, which has been designed and manufactured (in collaboration with the French optical company SESO) for the national Japanese 8 GeV storage ring Spring-8. The device consists of two 150 mm long modules assembled side-by-side. It exhibits superior surface quality with respect to previously manufactured long piezoelectric bimorph mirrors, as the junctions between modules do not introduce any distortion on the reflecting surface. The mirror can effectively compensate low frequency components of the figure error/waviness left by polishing. Two different simple optimisation methods have been validated: ex-situ in the metrology lab (Adaptive Optics correction and control algorithm) and, for the first time, in-situ at the beamline (Hartmann test). After optimisation with coherent x-rays at the 1 km long SPring-8 beamline, elliptical shaping was achieved with sub (mu) rad level precision for the slope error rms. The associated height error is as small as 8 nm rms. over 200 mm illuminated length. An extremely sharp gaussian 8 micrometers FWHM wide spot size was obtained by vertically demagnifying the undulator source. It has also been demonstrated that it is possible to bend the mirror to an arbitrary, user-defined, shape; i.e. sinusoidal.
The aim of this paper is to review the performances of the multi-segmented piezoelectric bimorph mirrors currently installed at the European Synchrotron Radiation Facility (ESRF). These innovative devices effectively combine the possibility of varying dynamically the average spherical bending radius (active mode) with the capability of acting locally on the reflecting surface shape (adaptive mode). A first generation consisting of two prototypes (450 and 750 mm long) was completely characterized in the ESRF metrology laboratory and the mirrors are installed and fully operational on the ID26 and ID32 beamlines since October 1997. A second generation prototype mirror (450 mm long) has been designed, manufactured, tested in the ESRF metrology laboratory, installed and commissioned at ID26 in early 1998. This last mirror exhibits sub-(mu) rad residual slope error rms in its central portion, 1 angstrom rms averaged microroughness and can routinely achieve a vertical beam size as small as 7 micrometer FWHM at a focal distance of almost 3 m.
This paper gives an overview of the current performances of the ESRF multi-segmented piezoelectric bimorph mirrors. These devices effectively combine the possibility of varying dynamically the average spherical bending radius with the capability of acting locally on the reflecting surface shape. A first generation consisting of two prototypes was completely characterized in the ESRF metrology laboratory and the mirrors are installed and fully operational on the ID26 and ID32 beamlines since October 1997. Results obtained during the characterization and the commissioning of these devices are presented. A second generation prototype mirror has been designed, manufactured, tested in the ESRF meteorology laboratory, installed and commissioned at ID26 in 1998. This last mirror exhibits sub- (mu) rad residual slope error rms in its central portion, 1 angstrom rms averaged microroughness a d can routinely achieve a vertical beam size as small as 7 micrometers FWHM at a focal distance of almost 3 m.
Ray-tracing plays an essential role for the design of a synchrotron radiation beamline optics. Nevertheless, it can also be extremely useful during the commissioning phase of a beamline. At that moment, it is possible to include real surface figure errors in the computer simulation of the optical devices. The resulting focal spot size and photon flux values are the final targets for the experimental optimization and alignment of the optics setup. We report on extensive ray-tracing of the mirror systems of the two beamlines placed at the ESRF insertion device 12. Slope errors measured after mirror delivery are included in the calculations. It is demonstrated how slope errors with characteristic periodicity between 1 and ca. 1/20 of the mirror length can affect the focal spot shape, size and position. In particular, they can create structures or satellites in the focal spot. The distortions from the ideal shape are generated by the polishing process itself and are intrinsic to each single mirror. Comparison between the effects of slope errors in ray-tracing using either real (measured) surfaces or numerically generated ones are also reported.
Reflective optics operated at grazing angle of incidence has a good polarization transfer function and was preferred to focus or steer the X-ray beam on the ESRF beamline ID12A which is dedicated to X-ray dichroism. The present paper reports on the design of a double mirror device (VF-2M) that is located downstream with respect to the monochromator and can refocus the X-ray beam vertically very near the sample location. This system combines two identical mirrors (L equals 600 mm; W equals 40 mm; T equals 12 mm) made of bulk CVD-SiC which were polished to a very precise cylindrical shape: when no bending forces are applied, each mirror has a concave curvature radius of 1 km with a slope error
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