Small-angle X-ray scattering (SAXS) is a promising metrology technology for complex nanostructures in semiconductor manufacturing. However, parameter reconstruction based on SAXS measurement often faces challenges in achieving high precision and repeatability due to the increasing complexity of structures and the demands for precise measurement. To address these challenges, a correlation learning-based method is proposed to enhance the accuracy and reduce the uncertainty of the profile reconstruction in SAXS measurement. This method leverages the long short-term memory (LSTM) mechanism to capture and learn inherent parameter correlation effectively. The precision and reliability of the proposed method are demonstrated through the simulations of synthetic Si gratings. Our method exhibits remarkable measurement accuracy with an improvement of at least 13.9%, and the measurement repeatability is nearly 1.4 times higher compared to the previous learning-based methods. We expect that our approach will provide a novel solution for SAXS measurement, enabling accurate and reliable profile reconstruction of nanostructures.

Two-photon polymerization lithography is a technique that provides hundreds of nanometer resolution and full geometric freedom. Several X-ray polymer refractive lenses created by this technique were characterized using differential phase contrast imaging (DPCI) with a microfocus X-ray grating interferometer. The beam deflection angle and wavefront phase shift of the X-ray beam through the lens were obtained. Comparative tests using synchrotron radiation sources showed that the system could measure the surface shape of X-ray refractive lenses with an accuracy of 0.4 µm. This study is important for improving the fabrication process and focusing performance of X-ray refractive lenses.

Freestanding Zr filters are important devices for improving spectral purity in the extreme ultraviolet range of 7–20 nm, and their irradiation resistance directly determines their life and efficiency. We prepared multilayered Zr/B4C and Zr/Si filters using magnetron sputtering. Their transmittance reached a maximum of 23% (λ = 13.5 nm). Microwatt-radiation-induced structural changes in the filters were investigated at the metrology beamline (BL08B) of the National Synchrotron Radiation Laboratory. The aging of the Zr filters was measured and analyzed. The experimental results revealed that the damage was noticeable on the irradiated filter surfaces with different states, suggesting that the main factors causing the degradation of the filters were oxidation and carbon contamination at the surfaces. Furthermore, the thermal stability of the Zr filters was studied by annealing, and the heat accumulation during the damage process was estimated using finite-element numerical simulations and X-ray photoelectron spectroscopy measurements. Silicide formation at the Zr-Si-O system interfaces was found to be key to enhancing the stability of the filters.

High-precision angle measurement of pulsars is critical for realizing pulsar navigation. Compared to visible light and radio waves, the wavelength of X-rays is incredibly short, which provides the possibility of achieving better spatial resolution. However, due to the lack of applicable X-ray apparatus, extracting the angle information of pulsars through conventional X-ray methods is challenging. Here, we propose an approach of pulsar angle measurement based on spatially modulated X-ray intensity correlation (SMXIC), in which the angle information is obtained by measuring the spatial intensity correlation between two radiation fields. The theoretical model for this method has been established, and a proof-of-concept experiment was carried out. The SMXIC measurement of observing angles has been demonstrated, and the experimental results are consistent with the theoretical values. The potential of this method in future applications is discussed, and theoretically, the angular measurement at the level of micro-arcsecond can be expected. The sphere of pulsar navigation may benefit from our fresh insights.

The X-ray free-electron laser (XFEL), a new X-ray light source, presents numerous opportunities for scientific research. Self-amplified spontaneous emission (SASE) is one generation mode of XFEL in which each pulse is unique. In this paper, we propose a pinhole diffraction method to accurately determine the XFEL photon energy, pulses’ photon energy jitter, and sample-to-detector distance for soft X-ray. This method was verified at Shanghai soft X-ray Free-Electron Laser (SXFEL). The measured average photon energy was 406.5 eV, with a photon energy jitter (root-mean-square) of 1.39 eV, and the sample-to-detector distance was calculated to be 16.61 cm.

In this paper, the influence of the delay time between the pre-pulse and the main pulse on the double-pass amplified 46.9 nm laser was studied for the first time, to the best of our knowledge, by using a high-precision polished SiC slice as a rear mirror. The temporal and spatial characteristics of the output laser were measured separately to investigate the effect of the delay time on the laser characteristics. The energy of the double-pass amplified laser was between 510 µJ and 890 µJ. In addition, a theoretical model of double-pass amplification was established to analyze the effect of the delay time on the double-pass amplified 46.9 nm laser.

In this paper, a simple theoretical model combining Monte Carlo simulation with the enthalpy method is provided to simulate the damage resistance of B4C/Si-sub mirror under X-ray free-electron laser irradiation. Two different damage mechanisms are found, dependent on the photon energy. The optimum B4C film thickness is determined by studying the dependence of the damage resistance on the film thickness. Based on the optimized film thickness, the damage thresholds are simulated at photon energy of 0.4–25 keV and a grazing incidence angle of 2 mrad. It is recommended that the energy range around the Si K-edge should be avoided for safety reasons.

Curved crystal imaging is an important means of plasma diagnosis. Due to the short wavelengths of high-energy X rays and the fixed lattice constant of the spherical crystal, it is difficult to apply the spherical crystal in high-energy X-ray imaging. In this study, we have developed a high-energy, high-resolution X-ray imager based on a toroidal crystal that can effectively correct astigmatism. We prepared a Ge 〈5 1 1〉 toroidal crystal for backlighting Mo Kα1 characteristic lines (∼17.48 keV) and verified its high-resolution imaging ability in high-energy X-ray region, achieving a spatial resolution of 5–10 µm in a field of view larger than 1.0 mm.

Non-interferometric X-ray quantitative phase imaging (XQPI), much simpler than the interferometric scheme, has provided high-resolution and reliable phase-contrast images. We report on implementing the volumetric XQPI images using concurrent-bidirectional scanning of the orthogonal plane on the optical axis of the Foucault differential filter; we then extracted data in conjunction with the transport-intensity equation. The volumetric image of the laminate microstructure of the gills of a fish was successfully reconstructed to demonstrate our XQPI method. The method can perform 3D rendering without any rotational motion for laterally extended objects by manipulating incoherent X-rays using the pinhole array.

A new type of X-ray fiber dosimeters is proposed that is based on the X-ray response of CsPbBr3 perovskite-quantum-dots (PQDs) activated silica fiber. Such a fiber sensor is constructed by covering a multimode silica fiber with PQDs embedded glass powders using a transparent high-temperature glue. Under X-ray irradiation, the fiber sensor emits bright green light at 525 nm, which can be readily recorded by a CCD spectrometer. The integrated radioluminescence intensity has an excellent linear response to the X-ray dose. Study is given to the fiber sensor concerning its thermal stability in a temperature range of room temperature up to 300°C, resistance to water erosion, and prolonged X-ray irradiation. The results verify that the proposed fiber sensor has the advantages of good thermal stability, chemical durability, and radiation hardness. The studied X-ray fiber sensor holds promise to be used in a real-time, in-situ, and remote radiation dose monitoring.

At present, reconstruction of megapixel and high-fidelity images with few measurements is a major challenge for X-ray ghost imaging (XGI). The available strategies require massive measurements and reconstruct low-fidelity images of less than 300×300 pixels. Inspired by the concept of synthetic aperture radar, synthetic aperture XGI (SAXGI) integrated with compressive sensing is proposed to solve this problem with a binned detector in the object arm. Experimental results demonstrated that SAXGI can accurately reconstruct the 1200×1200 pixels image of a binary sample of tangled strands of tungsten fiber from 660 measurements. Accordingly, SAXGI is a promising solution for the practical application of XGI.

Carbon fiber (CF)/pyrolytic graphite (PG) composites are promising structural materials for molten salt reactors because of their superior performance. Due to the minor density difference between CF and PG, existing methods are impractical for efficient three-dimensional characterization of CF/PG composites. Therefore, in this study, a method based on in-line phase-contrast X-ray microtomography was developed to solve the aforementioned problem. Experimental results demonstrate that the method is suitable for comprehensive characterization of CF/PG composites. The relationship between the microporous defects and fiber orientations of such composites was also elucidated. The findings can be useful for improving the manufacturing process of CF/PG composites.

In spectral diagnostic physics experiments of inertial confinement fusion, the spectral signal is weak due to the low diffraction efficiency when using bent crystals. A spectral diagnostic instrument with high efficiency and wide spectral range is urgently needed. A multi-curvature bent crystal with multi-energy focusing ability is proposed based on the traditional conical crystal geometry. It has advantages of wide spectral range, strong focusing ability, and high spectral resolution. It also can eliminate the imaging aberration in principle due to rotational symmetry for the incoming X rays. A spectral diagnostic experiment based on a fabricated multi-curvature α-quartz crystal was accomplished using a titanium X-ray tube of the bent crystal, and the corresponding experimental data using a plane α-quartz crystal was also acquired to demonstrate the strong focusing ability. The result shows that the Kα intensity of the multi-curvature α-quartz crystal is 157 times greater than that of the plane crystal, and the corresponding energy range is about 4.51–5.14 keV. This diagnostic instrument could be combined with a streak camera at a vertical direction so as to intensify the diffracted X-ray signal with a wide spectral range.

A Schwarzschild microscope with a numerical aperture of 0.2 and a magnification of 130 in a 100 μm field of view (FOV) is designed and is working at 13.5 nm. Meanwhile, a CCD is used as a detector with a pixel size of 13 μm×13 μm and imaging area of 13 mm×13 mm. The imaging quality with tolerances of system and errors of mirrors are considered. We obtain that the best on-axes object resolution can be up to about 200 nm, the average value is 230 nm, and the resolution is about 360 nm at 80 μm FOV.

We present a simple method to measure the spatial coherence of hard x-ray beams. Based on the convolution of Gaussian functions, we analyze the diffraction patterns of a grating irradiated by partially coherent hard x rays with a constrained beam diameter. The spatial coherence properties of an x-ray beam are obtained from the width of the diffraction peaks with high accuracy. The results of experiments conducted by combining a pinhole with a grating show a good agreement with our calculation using the Gaussian–Schell model.

Full-field x ray nano-imaging (FXNI) is one of the most powerful tools for in-situ, non-destructive observation of the inner structure of samples at the nanoscale. Owing to the high flux density of the third-generation synchrotron radiation facility, great progress is achieved for FXNI and its applications. Up to now, a spatial resolution of 20 nm for FXNI is achieved. Based on the user operation experiences over the years at the Shanghai Synchrotron Radiation Facility (SSRF) x ray imaging beamline, we know lots of user experiments will rely on a large range of spatial resolutions and fields of view (FOVs). In particular, x ray microscopes with a large FOV and a moderate spatial resolution of around 100 nm have a wide range of applications in many research fields. Driven by user requirements, a dedicated FXNI system is designed and constructed at the SSRF. This microscope is based on a beam shaper and a zone plate, with the optimized working energy range set to 8–10 keV. The experimental test results by a Siemens star pattern demonstrate that a spatial resolution of 100 nm is achieved, while an FOV of 50 μm is obtained.

Complementary analysis techniques are applied in this work to study the interface structure of Mo/Si multilayers. The samples are characterized by grazing incident x-ray reflectivity, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and extreme ultraviolet reflectivity. The results indicate that the layer thickness is controlled well with small diffusion on the interface by forming MoSi2. Considering MoSi2 as the interface composition, simulating the result of our four-layer model fits well with the measured reflectivity curve at 13.5 nm.

The vacuum-sealed miniature modulated x-ray source (VMMXS) with a hot cathode is fabricated via the single-step brazing process in a vacuum furnace. An experiment following the VMMXS is implemented to present its performances, including the influence of grid electrode potential on x-ray intensities. The modulation type of the grid electrode as a switch is proposed, and its feasibility is successfully demonstrated. It is noteworthy to discover a phenomenon for the first time, to the best of our knowledge, that the high repetition frequency grid pulse of the VMMXS has a significant effect on the x-ray intensity. The probable cause for this new finding is analyzed.

Nested multilayer mirrors are commonly used in X ray telescope structure to increase the collecting area. To balance the difficulty and cost of producing these mirrors, Wolter-I structures are replaced with conical Wolter-I structures, but these can lead to significantly poorer angular resolutions. In this Letter, we consider changing one of the mirror shapes (paraboloid or hyperboloid) of a Wolter-I structure to a conical mirror shape, while the other mirror shape remains a quadric surface-type structure, which can thus ensure the imaging quality. The cone-hyperboloid structure is nested to obtain on-axis angular resolution and off-axis images.

We describe the design and capabilities of the x-ray excited optical luminescence (XEOL) technique at the scanning transmission x-ray microscopy beamline (BL08U1A) of the Shanghai Synchrotron Radiation Facility. The detection system is a functional expanding of the original end station, making full use of its precision positioning stages. The simultaneous collection of XEOL and total electron yield spectra is realized using homemade software when the excitation energy is scanned. The setup is validated by the 2D near-edge x-ray absorption spectroscopy (NEXAFS) XEOL mapping across the O K-edge of a nanostructured ZnO sample. The ability to detect the signal of very weak light-emitting material is verified by using TiO2 nanopowder.

A tomography device based on a conventional laboratory x ray source, polycapillary parallel x ray lens (PPXRL), and polycapillary collimating x ray lens (PCXRL) is designed. The PPXRL can collect the divergent x ray beam from the source and focus it into a quasi-parallel x ray beam with a divergence of 4.7 mrad. In the center of quasi-parallel x ray beam, there is a plateau region with an average gain in power density of 13.8 and a diameter of 630 μm. The contrast of the image can be improved from 28.9% to 56.0% after adding the PCXRL between the sample and the detector.

A four-channel Kirkpatrick–Baez microscope working at multiple energy bands is developed for multiframe X-ray imaging diagnostics at the Shenguang-II laser facility. The response to the multiple energy bands is realized by coating the double-periodic multilayers on the reflected surfaces of the microscope. Because of the limited size of the microstrips in the X-ray framing camera, the image separation is controlled by the conical angle of the reference cores during microscope assembly. This study describes the optical and multilayer design, assembly, and alignment of the developed microscope. The microscope achieves a spatial resolution of 4–5 mm in the laboratory and 10–20 mm at Shenguang-II laser facility within a 300 mm field of view. The versatile nature of the developed microscope enables the multiple microscopes currently installed in the laser facility to be replaced with a single, multipurpose microscope.

A time-resolved multispectral X-ray imaging approach with new version of multi-channel Kirkpatrick-Baez (KB) microscope is developed for laser plasma diagnostics at the kilojoule-class Shenguang-II laser facility (SG-II). The microscope uses a total external reflection mirror in the sagittal direction and an array of multilayer mirrors in the tangential direction to obtain multiple individual high-resolution, highthroughput, and quasi-monochromatic X-ray images. The time evolution of the imploded target in multiple X-ray energy bands can be acquired when coupled with an X-ray streak camera. The experimental result of the time-resolved 2.5 and 3.0 keV dual-spectral self-emission imaging of the undoped CH shell target on SG-II is given.

The computed tomography imaging of a local region inside a sample with a size larger than the field of view is particularly important for synchrotron X-ray imaging. In this letter, an improved algorithm is proposed to reconstruct the local structure inside a sample using almost completely local data. The algorithm significantly reduces the X-ray radiation dose and improves computational efficiency. Simulation results show that the new algorithm works well and has a higher reconstruction precision than previous methods, as confirmed by experimental results carried out at the Shanghai Synchrotron Radiation Facility.

We report a design for one nanometer X-ray focusing by a complex refractive lens, which is capable of focusing 20 keV X-rays down to a lateral size of 0.92 nm (full-width at half-maximum (FWHM)) and an axial size of 98 nm (FWHM) with intensity gain of 49050. This complex refractive lens is comprised of a series of kinoform lenses, whose aperture is gradually matched to the converging trace of the X-ray beam so as to increase the numerical aperture (NA). The theoretical principle of the proposed complex refractive lens is presented. The NAs of these lenses are calculated. The numerical simulation results demonstrate that the proposed design can focus the X-ray beam into sub-nanometer while remaining high gain.

A four-channel multilayer Kirkpatrick-Baez (KB) microscope is developed for the 8-keV X-ray imaging of experiments on laser inertial confinement fusion (ICF). A periodic multilayer that works at 8 keV and with a grazing incidence angle of 1.0o is coated on reflective surfaces to achieve a spatial resolution higher than 5 \mu m and an effective solid angle higher than ~10-7 sr. A precise assembly is realized by a conical reference cone to couple with an X-ray framing camera. This study provides detailed information on an optical and multilayer design, assembly method, and experimental results with a Cu X-ray tube. The instrument provides a high-resolution and high-throughput X-ray image for backlit or self-emission imaging of laser plasma at Cu K\alpha line radiation in Shenguang series laser facilities.

K-shell X-ray emission from a Cu nanowire target irradiated by an ultraintense femtosecond laser pulse is studied using an elliptically bent quartz crystal and imaging plate. The designed bent crystal spectrometer has better spectral resolution, which is higher than 1 000. The absolute K radiation photon yields are obtained from the experimental results and the Monte-Carlo model. The conversion efficiency of the Cu K line is estimated to be 0.019% from the interaction of 4 J, 50-fs laser pulse irradiated on a Cu nanowire target. The high yield of K shell X-ray has important applications in X-ray emission source.

A WSi2/Si multilayer, with 300 bi-layers and a 2.18-nm d-spacing, is designed for X-ray monochromator application. The multilayer is deposited using direct current magnetron sputtering technology. The reflectivity of the 1st-order Bragg peak measured at E=8.05 keV is 38%, and the angular resolution (\Delta \theta/\theta) is less than 1.0%. Fitting results of the reflectivity curve indicate a layer thickness drift of 1.6%, mainly accounting for the broadening of the Bragg peaks. The layer morphology is further characterized by transmission electron microscopy, and a well-ordered multilayer structure with sharp interfaces is observed from the substrate to the surface. The material combination of WSi2/Si is a promising candidate for the fabrication of a high-resolution multilayer monochromator in the hard X-ray region.

Optical design of nested conical Wolter I X-ray telescope covering energy band from 1 to 30 keV is investigated systematically. Recurrence relation of the nested structure is deduced, and the impact of the initial parameters on the performance is analyzed. Due to the need for hard X-ray astronomical observations in China, the initial structure is presented, for which six groups ofW/B4C aperiodic multilayer coatings between the innermost and the outermost shell of the mirror are designed. The effective area, resolution, and field of view are calculated in the simulation. The results show that the effective area can achieve 71 cm2 and the field of view can achieve 13′ at 30 keV. The resolution is estimated to be ~10" in half-power diameter.

A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intensity distribution near the focus is derived for a plano-concave compound refractive X-ray lens. Moreover, the computer codes are developed and some results of 3D focusing performance for a compound refractive X-ray lens with Si material are shown and discussed.

A theoretical method based on the diffractive theory is used for predicting three-dimensional (3D) focusing performances of the compound X-rays refractive lenses (CRLs). However, the derivation of the 3D intensity distribution near focus for the X-ray refractive lenses is quite complicated. In this paper, we introduce a simple theoretical method that is based on the first and second moments in the theory of probability. As an example, the 3D focusing performance of a CRL with Si material is predicted. Moreover, the results are compared with those obtained by the diffractive theory. It is shown that the method introduced in this paper is accurate enough.

The X-ray spectrum emitted from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-II Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Fraunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Fraunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.

We use a varied line-spacing (VLS) grating to improve the performances of the constant-length Rowland-circle spherical grating monochromator. The translation distance of the mirror-grating tank in a scan of certain wavelength range will get much shorter. This will make the instrument easier to realize. Based on the principle of monochromator, we study how to optimize the optical system with a VLS grating in detail. The main imaging performances of the instrument are also evaluated.