The hard X-ray adaptive mirror optics will play an important role at next generation light sources. A dynamic mirror bender with capacitive sensor array as an in-situ mirror profiler is used for initial test for hard x-ray zoom optics has been designed and constructed. Previous work showcases the dynamic control of this elliptically bent hard X-ray mirror through applying a combination of neural networks algorithm and feedback control. In this paper, we present further control enhancement with machine learning techniques through optimization of the number and placement of the capacitive sensors and new sensor calibration with video-based coordinate measuring machine.
We will present the design for the In-Situ Nanoprobe (ISN) beamline that is being developed as part of the Upgrade of the APS storage ring with an MBA magnetic lattice. The ISN will provide large working distance of 60 mm for in-situ and operando environments, and a small spot of 20 nm (25 keV) for imaging materials with small defects and functional components. To achieve both long working distance and small spot size, Kirkpatrick-Baez mirrors will be used as nanofocusing optics. The major contrast mechanisms will be XRF imaging for chemical characterization ptychography for transmission imaging with sub-10 nm resolution. Auxiliary diffraction capabilities will allow monitoring of phase change during in-situ studies. To achieve the demagnification required to achieve small spot sizes, the ISN instrument will be placed at a distance of 220 m from the x-ray source, in a satellite building outside the APS storage ring. The ISN will provide hard x-rays with photon energy between 4.8 keV and 30 keV, enabling access to the absorption edges of to most elements in the periodic system. The MBA lattice and insertion devices, coupled with the high reflectivity of the K-B mirror system, provide a very high coherent flux of above 4*1012 Ph/s at 5 keV, and 6*1012 Ph/s at 30 keV. This allows hierarchical imaging of large samples with very small spot size, as well as multidimensional imaging, such as 3D imaging and temperature change, or 2D imaging with change of several environmental parameters. The ISN will provide flow of fluids, gases, and variable temperature.
KEYWORDS: Mirrors, Hard x-rays, Machine learning, Control systems, Sensors, Profilometers, Feedback control, In situ metrology, Adaptive optics, Control systems design
This article showcases the high-resolution control of an elliptically bent hard X-ray mirror optics at the Advanced Photon Source. The mirror uses a compact laminar flexure bending mechanism to achieve elliptical shapes covering a large range of focal distances. An array of capacitive sensors are used as a surface profiler for in-situ monitoring of the mirror shape. Machine learning and control techniques were used to change the mirror shape and focus the incident X-ray at predefined focal planes. The mirror surface shape error can be controlled to be within 40 nm rms with high repeatability. This technique gives the capability to focus incident X-ray beam within a range of focal distances corresponding to shape deformation range of a mirror optics. This work would be beneficial for controlling similar adaptive optics for multiple adaptive optics systems.
Mirror-based zoom optics systems can offer variable focal spot sizes over a wide range, which is essential for coherent nanoprobe beamlines, such as the proposed Atomic beamline in the Advanced Photon Source (APS) upgrade project. The success of the zoom mirror system in the nano-focusing regime requires the development of high-precision deformable mirrors, in-situ surface profilers and wavefront sensors, and advanced feedback control system. A prototype 1-D zoom mirror system consists of two vertical focusing mirrors was designed, assembled, and tested at the APS 1-BM beamline. The system consists of a bender-based mirror with a capacitive-sensor- array-based real-time mirror profiler, a bimorph adaptive mirror, and a grating interferometer for the wavefront monitoring. In this work, we present the design and test results of the prototype system demonstrating its zoom focusing capability.
An ongoing collaboration among four US Department of Energy (DOE) National Laboratories has demonstrated key technology prototypes and software modeling tools required for new high-coherent flux beamline optical systems. New free electron laser (FEL) and diffraction-limited storage ring (DLSR) light sources demand wavefront preservation from source to sample to achieve and maintain optimal performance. Fine wavefront control was achieved using a novel, roomtemperature cooled mirror system called REAL (resistive element adjustable length) that combines cooling with applied, spatially variable auxiliary heating. Single-grating shearing interferometry (also called Talbot interferometry) and Hartmann wavefront sensors were developed and used for optical characterization and alignment on several beamlines, across a range of photon energies. Demonstrations of non-invasive hard x-ray wavefront sensing were performed using a thin diamond single-crystal as a beamsplitter.
The Transmission X-ray Microscope (TXM) at beamline 32-ID-C of the Advanced Photon Source (APS) is a high throughput instrument with high spatial resolution for operando nano-tomography experiments [1]. Recently, a flexural nanopositioning stage system has been designed, and constructed at the APS for a set of JTECTM Kirkpatrick-Baez (KB) mirrors to be installed at the beamline 32-ID-C station. It will focus X-ray down to a 15-20 nm focal spot that will serve as a point source for projection microscopy. Many flexural stages in the stage system are using the same designs developed by APS for the beamline 34-ID-E [2]. However, the new stage system configuration is optimized for the operation conditions at the APS 32-ID-C to accommodate large nano-tomography sample stages. The experiences gained from this new flexural nanopositioning stage system design will benefit designs of K-B mirror nanofocusing stages for other x-ray nanoprobe beamline instruments at the APS-Upgrade project, especially for the In-Situ Nanoprobe instrument design. The mechanical design of the flexural stages, as well as its preliminary mechanical test results with laser interferometer are described in this paper.
Using a compact laminar overconstrained flexure bending mechanism and a capacitive sensor array, a precision compact mirror bending mechanism for 300-mm long hard x-ray mirror has been designed and constructed to perform initial test for x-ray zoom optics as a part of an Argonne Laboratory-Directed Research and Development project at the Advanced Photon Source. A Finite Element Model (FEM) of the mirror bender was created with commercial simulation software. An iterative process of simulations were run to predict accurate bending parameters for the flexure bending mechanism.The FEM simulation demonstrated a result of an elliptically bent trapezoid mirror surface that fit with desired elliptical mirror profile within ±20 nanometers over 86% of the mirror’s measured length. The iteration process of model refinement, results of the finite element simulations, and preliminary test of the capacitive sensor array are discussed in this paper.
The Advanced Photon Source Upgrade (APS-U) project will construct several new, best-in-class beamlines and enhancements to existing beamlines to exploit the massive increase in coherent flux enabled by the new storage ring lattice. APS-U will also enhance several existing beamlines to boost their performance. X-ray tomography is a common imaging mode for several of these beamlines, so there is demand for the highest-precision rotation of the sample. For example, the In Situ Nanoprobe (ISN, 19-ID), a next-generation hard x-ray nanoprobe, will use x-ray fluorescence tomography and ptychographic 3D imaging as key imaging modes with a spot size of 20 nm. It will require <100 nm runout and single-micro-radian wobble errors of the rotation stage to achieve full 3D resolution. Such precise requirements for a rotation stage can be achieved with air bearing rotation stages. However, this approach puts constraints on sample positioning design in terms of the sample environment (air bearing stages are generally not vacuum compatible) and the large mass of air bearing rotation stages. Mechanical bearing stages do not equal the precision runout/wobble specifications of air bearings. In order to use mechanical stages and approach air bearing level precision, the errors of the mechanical stage have to be measured precisely. We have then designed a metrology system using interferometer or capacitive sensors for the nanopositioning support lab as a diagnostic tool and to be portable for quality assurance testing of stages at the beamline.
The ever-increasing spatial resolution of nanofocusing hard x-ray optics, coupled with the need for long working distances and spectroscopic imaging, requires stages that translate optics and samples over millimeters with trajectory errors of under 10 nm. To overcome the performance limitations of precision ball-bearing-based or roller-bearing-based linear stage systems, compact vertical and horizontal linear nanopositioning flexure stages, with centimeter-level travel range, have been designed and tested at the Advanced Photon Source (APS) for x-ray instrumentation applications. The mechanical design and finite element analyses of the flexural stages, as well as its preliminary test results with laser interferometers are described in this paper.
With the current drive towards diffraction limited storage rings, hard x-ray optics will require subsequent increases in positioning accuracy over large travel ranges. Nanometer-level precision positioning requires the use of compliant mechanisms to remove friction and backlash type errors. Ideally, the compliant mechanism is compliant in the direction of desired travel and rigid in all other directions. However, in reality, there is still compliance in these other directions, particularly for flexure pivots, which lead to parasitic trajectory errors. In this paper we analyze the trajectory errors of a linear guiding mechanism, composed of commercially available C-Flex Bearing Co. Inc. and Riverhawk Co. flexure pivots, using finite element analysis and experimental measurements. The guide is designed as an assembly of double parallel 4-bar type deformation compensated linear guiding mechanisms, and incorporates a novel 1:2 stabilizer unit to control the middle-bar. The focus of the analysis is on the trajectory errors caused by rotation center shift, manufacturing tolerances, flexure pivot size, assembly tolerances, and includes a discussion of methods to mitigate these errors.
The 3-D X-ray diffraction microscope is a new nondestructive tool for the three-dimensional characterization of mesoscopic materials structure. A flexural-pivot-based precision linear stage has been designed to perform a wire scan as a differential aperture for the 3-D diffraction microscope at the Advanced Photon Source, Argonne National Laboratory. The mechanical design and finite element analyses of the flexural stage, as well as its initial mechanical test results with laser interferometer are described in this paper.
Autocollimator-based long trace profiler requires precise angular calibration to perform accurate measurements for xray
mirrors. A prototype of a precision two-dimensional tip-tilting stage system has been designed and tested for a new
autocollimator-based long trace profiler at the Advanced Photon Source (APS), Argonne National Laboratory (ANL).
This flexural stage system is designed to meet challenging mechanical and optical specifications for producing high
positioning resolution and stability for angular calibration for autocollimator-based long trace profiler. It could also be
used as a precision mirror manipulator for hard x-ray nano-focusing with Montel mirror optics.
The mechanical design of a precision two-dimensional tip-tilting stage system as well as preliminary test results of its
precision positioning performance are presented in this paper.
Viscoelastic models are fit to shear moduli derived from geometrically focused surface waves (GFS) on human skin using viscoelastic wave theory. Unlike in previous studies on the analytical solution and experimental measurement of radially outward traveling surface waves, measurable radially inward traveling GFS waves can be generated over a wider range of frequencies as attenuation is countered by the converging nature of the wavefront. This enables a more accurate and broader assessment of both the shear storage and loss moduli of the material, which are expected to vary with frequency. In the present study, GFS waves are applied to human skin on the posterior side of the forearm using a scanning LASER Doppler vibrometer. Surface wave measurements can then be used to estimate the complex frequency dependent viscoelastic properties of biological tissue, which are affected by numerous pathologies. Using a phantom gel this technique was validated through comparison with other studies. It was found that spring-pot and fractional Voigt models yield a potentially stable model parameter for skin, but more study is needed to confirm. [Work supported by NIH: Grant # EB012142.]
Kirkpatrick-Baez (K-B) mirrors [1] are sophisticated x-ray micro- and nano-focusing tools for synchrotron radiation applications. A prototype of a modular x-ray K-B mirror mount system has been designed and tested at an optics testing beamline, 1-BM at the Advanced Photon Source (APS), Argonne National Laboratory (ANL). This compact, costeffective modular mirror mount system is designed to meet challenging mechanical and optical specifications for producing high positioning resolution and stability for various scientific applications with focused hard x-ray beams down to the 100-nanometer scale. The optomechanical design of the modular x-ray K-B mirror mount system as well as the preliminary test results of its precision positioning performance are presented in this paper.
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