Nanometer-scale optical imperfections challenge coherent X-ray beam applications, even with advancements in X-ray synchrotron facilities, such as the upgraded Advanced Photon Source. Piezoelectric bimorph mirrors offer adaptive control but face limitations from nonlinearities such as crosstalk, creep, and hysteresis. This work introduces a real-time, feedback-free controller inspired by the PID scheme and powered by tandem neural networks (TNN). Using task-specific datasets, the TNN-based system predicts actuator voltages with greater speed, accuracy, and stability than a single NN-based model. Ideal for real-time applications, such as adapting beam focus to dynamic sample sizes, it maintains precise control over radiation and wavefront quality. This advancement highlights artificial intelligence’s transformative potential for adaptive optics and nonlinear systems.
The advent of high-brilliance synchrotron radiation sources with low emittance and high degree of coherence has urged the development of super-smooth x-ray mirrors, which have sub-nanometer height errors and sub-50-nrad slope errors. To ensure the optical performance and avoid procuring significantly more expensive mirrors than necessary, knowledge of the mirror surface power spectral density (PSD) function is required over a wide spatial frequency range. In addition, a better understanding of the diffraction effects of different spatial frequencies is required to guide the specification of the mirror in the beamline design phase. In this work, two typical x-ray beam focusing conditions for the proposed APS upgrade are studied: the diffraction limited focusing and the demagnification dominated focusing. The effects of surface errors are studied using both the method described by Church and Takacs1 and numerical simulations with HYBRID2. Using this information, we show how the mirror specification depends on the mirror PSD.
Quartz has hundreds of strong Bragg reflections that may offer a great number of choices for making fixed-angle X-ray analyzers and polarizers at virtually any hard X-ray energies with selectable resolution. However, quartz crystals, unlike silicon and germanium, are chiral and may thus appear in two different forms of handedness that are mirror images. Furthermore, because of the threefold rotational symmetry along the c axis, the { h 1 h 2 h 3 L } and { h 2 h 1 h 3 L } Bragg reflections may have quite different Darwin bandwidth, reflectivity and angular acceptance, although they have the same Bragg angle. The design of X-ray optics from quartz crystals therefore requires unambiguous determination of the orientation, handedness and polarity of the crystals. The Laue method and single-axis diffraction technique can provide such information, but the variety of conventions used in the literature to describe quartz structures has caused widespread confusion. The current studies give detailed guidelines for design and fabrication of quartz X-ray optics, with special emphasis on the correct interpretation of Laue patterns in terms of the crystallography and diffraction properties of quartz. Meanwhile, the quartz crystals examined were confirmed by X-ray topography to have acceptably low densities of dislocations and other defects, which is the foundation for developing high-resolution quartz-based X-ray optics.
Measuring the electron source size is essential for determining the emittance of synchrotron radiation. Pinhole imaging is the most common technique which measures the source profile in all transverse directions. The grating interferometry technique measures the coherence function of the x-ray beam, which indirectly determines the source size. The newly developed phase-space beam position and size monitor (ps-BPM) system provide information on electron source properties: position, angle, size, and divergence. These three techniques were used to determine the source size at a bend magnet beamline at the Canadian Light Source. In this work, we compare experimental results from these measurements at the same time, which is used as a cross-calibration procedure for each method.
We report on interferometric measurements of the figure error of an ultra-precise mirror with the shape of an elliptical toroid for the diffraction limited focusing of hard x-rays from an undulator x-ray source. We describe measurement configurations using Fresnel type holograms and photon sieves, and evaluate the measurement uncertainty.
Utilization of an Si(331) beam conditioner together with an Si(111) double-crystal monochromator (DCM) enables the angular resolution of synchrotron X-ray topography to be increased by an order of magnitude compared with grazing-incidence topography or back-reflection topography conducted with the DCM alone. This improved technique with extremely small beam divergence is referred to as synchrotron X-ray plane-wave topography (SXPWT). This study demonstrates that the rocking curve width of 4H-SiC 0008 in PWT is only 2.5′′ and thus the lattice distortion at the scale of 1′′ will significantly affect the diffracted intensity. This work reports the ultra-high angular resolution in SXPWT which enables detailed probing of the lattice distortion outside the dislocation core in 4H-SiC, where the sign of the Burgers vector can be readily determined through comparison with ray-tracing simulations.
