Publications by authors named "John P Sutter"
Article Synopsis
- Advanced X-ray sources like synchrotron radiation facilities and X-ray free electron lasers aim for smooth beams in the far-field plane, but imperfections in optics can create fine structures in the beam images.
- This article builds on previous research regarding intensity uniformity in far-field images and introduces a new theoretical framework.
- The new approach simplifies assumptions about wavefront curvature and offers a quantitative way to assess the effects of optical errors, with results supported by X-ray experiments.
Article Synopsis
- The text discusses a software package designed for accurately calculating structure factors for X-ray optics using diffraction from crystals, with α-Quartz as a focus due to its challenging properties and relevance in high-resolution X-ray spectroscopy.
- The software accounts for the anisotropic and nonlinear temperature dependence of lattice parameters and atomic vibrations, proving more accurate than simpler isotropic models, with discrepancies in results potentially reaching 100% in some cases.
- The package is user-friendly, written in Python 3 for easy integration into other projects, and includes tools for identifying Bragg reflections based on specific energy and temperature criteria, along with instructions on the unique aspects of chiral quartz.
Ultra-SAXS can enhance the capabilities of existing synchrotron SAXS/WAXS beamlines. A compact ultra-SAXS module has been developed, which extends the measurable q-range with 0.0015 ≤ q (nm) ≤ 0.
View Article and Find Full Text PDFX-ray beams reflected from a single layer or multilayer coating are widely used for X-ray tomography, holography, and X-ray phase contrast imaging. However, the observed irregular stripe patterns from either unfocused or defocused beams often cause disturbing artifacts and seriously deteriorate the image quality. In this work, we investigate the origin of these irregular fine structures using the wave optics theory.
View Article and Find Full Text PDFArticle Synopsis
- Optical element error analysis is crucial in designing beamlines for synchrotron radiation and free-electron lasers, but traditional wave optics simulations are time-consuming, hindering early design stages.
- A new theoretical approach allows for quicker evaluations of optical performance degradation due to imperfections, treating these errors as perturbations that affect ideal performance.
- The approach helps define critical error ranges and shows that two different mirror surface errors with the same density can lead to varying intensity profiles, aiding designers in setting more accurate error tolerances.
Article Synopsis
- - B21 is a small-angle X-ray scattering (SAXS) beamline located at the Diamond Light Source in the UK, using a bending magnet source from a 3 GeV storage ring to generate high-intensity X-ray beams.
- - The setup includes advanced equipment like a double multi-layer monochromator and toroidal focusing optic, achieving a high photon delivery rate to a small focal spot, and offering automated and manual sample loading options.
- - Since 2013, B21 has been operational for users, providing effective measurement capabilities for various biological macromolecules due to its extensive scattering vector range and low background noise.
Article Synopsis
- The Diamond Light Source (DLS) beamline I15-1 utilizes high-energy X-rays (40-80 keV) to analyze atomic pair distribution functions (PDF).
- A specially designed, 1-meter-long multilayer-coated bimorph mirror focuses these X-rays into a precise spot size, optimizing their use in experiments.
- The mirror successfully achieved focal spots with a vertical width of less than 15 µm and demonstrated effective adjustments for varying focal positions, marking a significant advancement in synchrotron beamline technology.
Article Synopsis
- Active X-ray optics at synchrotron facilities have traditionally changed curvature slowly, often requiring expert oversight and lengthy setup times, limiting their dynamic use in experiments.
- This paper discusses the implementation of high-speed adaptive X-ray optics, allowing rapid adjustments in beam size and shape in under 10 seconds, which can greatly benefit experiments like macromolecular crystallography.
- The study demonstrates how innovations in mirror design and control can lead to stable X-ray beam sizes for over an hour after adjustments, marking a significant advancement in synchrotron and XFEL technologies.
The scanning four-bounce monochromator for beamline I20 at the Diamond Light Source.
J Synchrotron Radiat
September 2018
Article Synopsis
- The text describes a newly commissioned four-bounce crystal monochromator for the XAS beamline at Diamond Light Source, featuring a unique design with two independent rotary axes.
- The device maintains flux throughput without external feedback from 4 to 20 keV and is currently equipped with cryogenically cooled Si(111) crystals.
- Preliminary designs allow for the potential installation of an additional Si(311) crystal-set to increase the energy range to 34 keV, with experimental data supporting its mechanical stability and repeatability.
Aberration-free aspherical lens shape for shortening the focal distance of an already convergent beam.
J Synchrotron Radiat
November 2017
Article Synopsis
- A theoretical study investigates a compound refractive lens (CRL) with 48 consecutive surfaces designed to focus X-rays without aberration.
- It focuses on how the lens accepts converging X-rays from the downstream end and refracts them to a new focal point closer to the surface.
- The study identifies the optimal shape for this lens as a Cartesian oval and provides analytical computations and ray tracing to support its design for future nanofocusing applications.
Article Synopsis
- - Beam shaping for synchrotron X-rays is challenging due to limited coherence and strict optical tolerances, where tiny surface errors can lead to significant beam distortions.
- - To address these issues, researchers modified mirror surfaces with alternating concave and convex curvatures, creating mirrors that maintain a consistent X-ray beam size but lack adaptability for various experiments.
- - The introduction of deformable piezo bimorph mirrors allows for dynamic adjustments in beam size and shape, with a new theory enabling specific non-periodic curvature modifications that lessens beam striation and enhances performance.
Article Synopsis
- EXAFS studies on dilute samples often use large-area detectors, but these can produce 'glitches' due to issues with single-crystal monochromators that affect data quality.
- Glitches cause disruptions in the intensity of X-ray scattering and require advanced techniques, like multiple-beam dynamical diffraction theory, for proper interpretation.
- Research at the Diamond Light Source's I20-scanning beamline revealed that a novel fitting procedure can effectively normalize EXAFS data affected by glitches, improving accuracy in analyzing dilute samples.
Article Synopsis
- The X-ray birefringence imaging (XBI) technique is a new method that allows for detailed mapping of how materials with different orientations behave under certain conditions.
- This paper presents the first use of XBI on materials that show anisotropic molecular dynamics, specifically focusing on urea inclusion compounds with two different dibrominated guest molecules.
- The findings indicate that the effective optic axis of the X-ray birefringence is determined by the average orientation of the C-Br bonds over time, highlighting the relationship between molecular dynamics and X-ray behavior.
Piezo bimorph mirrors are versatile active optics used on many synchrotron beamlines. However, many bimorphs suffer from the `junction effect': a periodic deformation of the optical surface which causes major aberrations to the reflected X-ray beam. This effect is linked to the construction of such mirrors, where piezo ceramics are glued directly below the thin optical substrate.
View Article and Find Full Text PDFObtaining local reciprocal lattice vectors from finite-element analysis.
J Synchrotron Radiat
November 2008
Article Synopsis
- Engineers often use finite-element analysis to assess how single crystals deform under bending or thermal loads at synchrotron beamlines.
- ANSYS Workbench is a popular software choice for these simulations, providing insights into displacements, strains, and stresses.
- A new method has been developed to extract local reciprocal lattice vectors for X-ray diffraction calculations, applied to a specific double-crystal monochromator project at the Diamond Light Source.
The perfection of two commercial top-grade quartz crystal wafers has been investigated using Bragg reflection at theta(B)=89.77 degrees of a 2.0 meV bandwidth beam of 9.
View Article and Find Full Text PDFArticle Synopsis
- A new X-ray Michelson interferometer was tested at the SPring-8 beamline, building on the existing BBB interferometer design.
- The test involved using a piezo to adjust one mirror, which allowed researchers to observe changes in intensity related to path-length differences.
- The results confirmed the expected fringe patterns, highlighting the need for a stable environment due to the small mirror displacement necessary for accurate measurements.