We have been developing a transmission soft x-ray microscope utilizing Wolter mirrors at a soft x-ray beamline of SACLA. We upgraded the soft x-ray microscope to enable simultaneous visible light imaging and soft x-ray imaging. To achieve this, we divided the annular apertures of the condenser and objective Wolter mirrors into two sections, allowing for soft x-ray imaging with one part and visible light imaging with the other. Our microscopy allows imaging cells with fluorescent labels by visible light while observing them with water window soft x-rays, which is useful for studying living cells.

Short- and ultra-short-period multilayer (ML) structures play a crucial role in wavelength dispersive x-ray fluorescence (WD-XRF). In WD-XRF a ML serves as an analyzer crystal to disperse emission lines of light elements in the O-Kα – Al-Kα range (λ=2.36 – 0.834nm). For these reasons, MLs with periods ranging from 1.0 to 2.5nm are very interesting. Due to the short period, the reflectance of such MLs is extremely sensitive to interface imperfections. Our research focuses on synthesis and characterization of MLs with d-spacing between 2.5 nm and 1.0 nm, combining tungsten (W) absorber with B4C, Si and Al spacers. These combinations show high theoretical reflectance in the full range from C-Kα (4.48nm) all the way down to S-Kα (0.54nm). By optimizing the ion polishing process: ion species, energy, and polishing frequency, we show that a major improvement in reflectivity can be achieved: with the most optimal ion polishing process, a factor 2x in reflectivity was achieved for 1.0 and 1.1nm MLs, with a record reflectivity of almost 10% at lambda=0.84nm for 1.1nm W/Si.

Polarized neutrons are crucial for various research fields, but existing multilayer optics have limitations. By incorporating 11B4C into Fe/Si layers during deposition, we address these challenges. This method enhances reflectivity and polarization by creating smoother interfaces and optimizing scattering length density. Adding 15 at.% of 11B4C to Fe/Si multilayers improves reflectivity by 125% and polarization by 20%. It also reduces diffuse scattering and eliminates magnetic coercivity, making the layers magnetically soft. This enables saturation at low external fields. Our findings, supported by x-ray and neutron reflectivity measurements, suggest that integrating 11B4C into Fe/Si multilayers improves neutron optics, promising better performance in scattering facilities.

Nanometer-thin multilayers are crucial in various optical applications, from lithography to x-ray instruments. The interface sharpness between layers determines reflectivity losses. Metrology is vital for understanding the interface forming mechanisms at an atomic level. Single techniques like TEM and XRR provide atomic or electronic density resolution, while XPS data about the compound formation. We extended our metrology portfolio with two in-house customized techniques: XSW and LEIS. The XSW technique is used for the analysis of thin film atomic profiles. The specific analysis of the background in LEIS spectra was used to analyze the interface with sub-nm resolution. A hybrid metrology approach combining these techniques is essential for efficient multilayer characterization. The metrology-driven multilayer growth optimization will be illustrated as an example of W/Si multilayers. By analyzing x-ray reflectivity and XSW data with a single model, we revealed the formation of WSix at W/Si interfaces, leading to poor performance. The introduction of 0.1 nm B4C diffusion barriers improved reflectivity, showing their direct contribution to enhanced performance.

X-ray fluorescence imaging (XFI) provides the non-invasive tracking of entities like immune cells using dedicated markers in objects of different sizes. XFI typically uses synchrotron pencil beams to reach a high spatial resolution. To minimize the applied dose and scan time, a coarse scan can precede a finer one. A unique approach utilizing Bragg reflection at a cylinder optic with mosaic graphite-based material significantly enlarges the fine x-ray beam. Experiments at the P21.1 beamline at PETRA III synchrotron reveal a remarkable beam enlargement of 10 to 20 times, showcasing a 68% dose reduction and 62% scanning time reduction. This innovative technique holds promise for efficient and low-dose XFI applications.

While there are many variations of an Inelastic X-ray Scattering (IXS) spectrometer, the figure of merit is often the energy resolution and the throughput. As part of the LCLS-II-HE project, the DXS team is developing a hard X-ray IXS spectrometer with a resolution of 5 meV at 11.215 keV. The spectrometer relies on a so-called post-sample-collimation scheme, and this high degree of resolution comes with stringent precision and stability requirements. SHADOWOui is used to simulate the setup and analyze the tolerance of 4 optics’ axis (translation, pitch, yaw, roll) and the miscut angle of the channel-cut crystal of the design. The simulation indicates that a 5 meV resolution is achievable by ensuring stringent pitch and vertical translation tolerances. Furthermore, the simulation suggests that a miscut angle of 77 degrees, which necessitates high-quality crystal manufacturing, is optimal.

Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic technique for analyzing elementary excitations. However, this process is inefficient and thus difficult to apply to imaging. We propose to stimulate the RIXS (SRIXS) process using a soft x-ray free-electron laser (SXFEL), increasing the photon yield by up to 6 orders of magnitude [Higley, Commun. Phys. 5 83 (2022)]. By designing a new achromatic full-field twin Wolter mirror microscope and multi-aperture grating, it should become possible to measure SRIXS by imaging the full x-ray spectrum at many spatial points simultaneously. To test the feasibility of SRIXS imaging, we simulate the SRIXS signal strength with a three-level Maxwell-Bloch model. Using the parameters of the SACLA BL1 SXFEL, we show that SRIXS imaging is feasible, requiring a peak intensity of 1016 W/cm2 and sub-micron focus size, readily achievable with the proposed microscope.

Synchrotron Thailand is planning to build a new ring shortly. One of the main components of the beamline is the optic. The high-precision multilayer coating system for x-ray optics was created to develop knowledge, skills, and creativity. In 2021-2024, we received a fundamental fund from the government to build a coating system for x-ray optics. We started from the conceptual design until the fabrication machinery in-house. I will talk about design, progress, and collaboration in this topic.

Reflection gratings are critical components to successful x-ray spectroscopes and represent important priorities for future NASA observatories. As such, significant research efforts have been invested to improve mirror and grating fabrication, resulting in increased collecting area and improved mirror performance. However, residual stresses induced by reflective coatings continue to present challenges, causing mirror deformation, degradation of spectral resolution, and decreased scientific performance. Though macro stresses on thicker layers are more easily calculated, localized stress distributions and the stress response of nanoscale layers (5 to 30nm) are not well understood and can be difficult to measure. This study demonstrates synchrotron x-ray diffractive (XRD) methods using the sin^2⁡ψ technique to better characterize and minimize the stress nanoscale reflective layers (5 to 30nm) for applications in x-ray optics. Residual stresses are spatially mapped across an optic and analyzed at different deposition conditions and anneal treatments. High-Z materials (Ir, Pt, Au) have been chosen for this study due to their favorable reflectivity over soft x-rays.