B₄C/Pd multilayers with small d-spacing can easily degrade in the air, and the exact degradation process is not clear. In this work, we studied the chemical modification of B₄C films and B₄C/Pd double layers stored in four different environments: a dry nitrogen environment, the atmosphere, a dry oxygen-rich environment, and a wet nitrogen environment. The XANES spectra of the B₄C/Pd layers placed in a dry oxygen-rich environment showed the most significant decrease in the σ* states of the B–C bonds and an increase in the π* states of the B–O bonds compared with the other samples. X-ray photoelectron spectroscopy (XPS) measurements of the samples placed in a dry oxygen-rich environment showed more intensive B-O binding signals in the B₄C/Pd layers than in the single B₄C film. The results of the Fourier-transform infrared spectroscopy (FTIR) showed a similar decrease in the B–C bonds and an increase in the B–O bonds in the B₄C/Pd layers in contrast to the single B₄C film placed in a dry oxygen-rich environment. We concluded that the combination of palladium catalysis and the high content of oxygen in the environment promoted the oxidization of boron, deteriorated the B₄C composition.

The laterally graded multilayer collimator is a vital part of a high-precision diffractometer. It is applied as condensing reflectors to convert divergent X-rays from laboratory X-ray sources into a parallel beam. The thickness of the multilayer film varies with the angle of incidence to guarantee every position on the mirror satisfies the Bragg reflection. In principle, the accuracy of the parameters of the sputtering conditions is essential for achieving a reliable result. In this paper, we proposed a precise method for the fabrication of the laterally graded multilayer based on a planetary motion magnetron sputtering system for film thickness control. This method uses the fast and slow particle model to obtain the particle transport process, and then combines it with the planetary motion magnetron sputtering system to establish the film thickness distribution model. Moreover, the parameters of the sputtering conditions in the model are derived from experimental inversion to improve accuracy. The revolution and rotation of the substrate holder during the final deposition process are achieved by the speed curve calculated according to the model. Measurement results from the X-ray reflection test (XRR) show that the thickness error of the laterally graded multilayer film, coated on a parabolic cylinder Si substrate, is less than 1%, demonstrating the effectiveness of the optimized method for obtaining accurate film thickness distribution.

Extreme ultraviolet polarizers are crucial for in-depth investigations of light–matter interaction and cutting-edge applications in modern optics. Here, we propose a strategy for extreme ultraviolet wire grid polarizers with superior performance based on vacuum guiding. Owing to the suitable material absorption and vacuum guiding effect, the designed polarizers exhibit an inverse polarization effect and achieve polarization extinction ratios exceeding 100 at various extreme ultraviolet bright lines. Furthermore, the optimized a-silicon-based and molybdenum-based wire grid polarizers achieve the average transmissivity of the target polarization over 30% and 40% at 90–110 and 50–65 nm, respectively, while maintaining a polarization extinction ratio greater than 100. Comparisons with conventional devices further validate the exceptional performance of our device.

A multispectral extreme ultraviolet imaging system based on a separated multichannel Schwarzschild objective was developed for emission measurements of tokamak plasma, with a wide field of view, high spatial resolution, and multispectral resolution. Multiple energy responses were realized by depositing different multilayer coatings on each mirror, targeting the interesting spectral lines of common impurities, such as Ne, C, and W, observed in tokamak experiments. Direct-current magnetron sputtering in conjunction with mask reshaping was employed to fabricate highly uniform multilayers on large-curvature substrates, achieving a thickness control accuracy of ±0.1 nm. Furthermore, this paper proposes an assembly and adjustment scheme that transitions from single-channel centering to multichannel integration, ensuring high-precision alignment across all channels. The design, preparation, and experimental validation of the proposed system are reported. The system was experimentally validated in the Experimental and Advanced Superconducting Tokamak facility, successfully detecting all target spectral lines. The results of the study demonstrate the feasibility of electron temperature measurements using the proposed system.

Owing to the superior quality of the interface, WC/SiC multilayers have been considered promising candidates for X-ray Laue lenses in nano-focusing facilities and supermirrors in X-ray telescopes. To investigate the microstructure evolution in WC/SiC multilayers, a set of periodic multilayers was prepared with varied WC layer thicknesses ranging from 1.0 nm to 10.0 nm while keeping the thickness of the SiC layer constant at 3.0 nm. These samples were characterized using various analytical techniques, including GIXR, AFM, and XRD. An aperiodic WC/SiC multilayer sample was analyzed by TEM, EDX, and SAED to further study the chemical and structural changes while the thickness of the WC layer increased. The results indicate that the WC layer of the WC/SiC multilayer changes from amorphous to crystalline with increasing layer thickness. The crystalline state of the WC layer changes as the thickness increases. Meanwhile, the carbon atoms migrates noticeably to the interface as the WC layer becomes thicker, which smoothens the interfacial defects caused by the crystalline state transition. This migration of carbon is one of the key factors contributing to the smooth interface in WC/SiC multilayers.

The diamond-turning process is a mean optical surface generation technique with high figure accuracy and surface finish. The diamond-turned surface has a significant diffraction effect introduced by the tool marks remaining on the surface, which heavily degrade the optical performance in the visible wavelength spectrum. The traditional approach that was used to eliminate this effect was polishing. In this paper, we present a method to find turning parameters that can generate an optical surface without diffraction effect directly by coupling a surface micro-topography model of a turned surface via the scattering theory. The surface micro-topography model of the turned surface reveals the relationship between tool marks and the diamond-turning parameters (DTPs). The scattering theory reveals the relationship between diffraction intensity distributions (DIDs) and surface micro-topography of the turned surface. Therefore, we obtained the relationship between DIDs and DTPs. The diffraction effect is considered to be eliminated when the first-order diffraction intensity is less than 0.01% of incidence intensity. The criterion of turning parameters for diffraction elimination is then obtained. Finally, turning experiments are performed to confirm the effectiveness of this method, and the diffraction-free surface finish is achieved.