Aiming at imaging to weak signal in a complex system, our research team proposes a method called move contrast X-ray imaging, which takes the advantage of the time evolution of modulation of each moving component to incident light field in a complex system, to differentiate the components and image them separately. Accordingly, the mutual interference between components is eliminated and the sensitivity to weak signals is improved significantly. Experimental results of angiography with low agent dose, agent-free imaging of water refilling along microvessels in plant branch, and sensitive tracking to ion migration in a electrolytic cell demonstrate the practicability of move contrast X-ray imaging of weak signals in complex systems while traditional methods fail. The concept of move contrast imaging is applicable to all wavelength, and the proposed method may find extensive applications in imaging of infrared and visible light bands.

A capillary X-ray lens works in a manner of total reflection of X-ray, which can be designed into different shapes to obtain various beams, such as quasi-parallel beams, micro focal spots, and ring beams, with a high gain in power density to meet different needs. Capillary X-ray lenses can regulate the X-ray of various X-ray sources, such as X-ray sources in the conventional laboratory, synchrotron radiation sources, laser-plasma X-ray sources, X-ray free-electron laser facilities, and X-ray sources in the galaxy. Additionally, capillary X-ray lenses can easily and economically facilitate the development of X-ray technology, and therefore, they play an important role in the development of X-ray science and technology with its wide applications. In this paper, the design, fabrication, and applications of capillary X-ray lenses are reviewed, and the further development of capillary X-ray lens technology in the future is discussed.

Extreme ultraviolet (EUV) and vacuum ultraviolet (VUV) high-performance thin film optical elements greatly improve the capability of high-precision observation, and contribute to the development of astronomy, materials, physics, and other disciplines. According to the different application requirements as well as physical and chemical properties of materials, the Institute of Precision Optical Engineering (IPOE) in Tongji University has successfully developed amounts of high-performance thin film mirrors, such as Mg/SiC, Sc/Si, Yb/Al, Al+LiF+eMgF2, and LaF3/MgF2, which can meet the requirements of application in whole EUV and VUV wavelength ranges (25--200 nm). These mirrors are already applied to domestic large-scale scientific instrument (from ground to space). This paper briefly introduces the research progress obtained by IPOE during the development of EUV and VUV thin film optical elements.

The X-ray nanofocusing techniques based on synchrotron radiation and free-electron laser facilities have become important ways to carry out cutting-edge scientific and technological research. Since the refractive indices of nanofocusing materials in X-ray regime are very close to unity, the X-ray focusing optics are very different from the traditional visible optics. The working principle of diffractive, refractive and reflective focusing optics commonly used in X-ray regime in the synchrotron field, and the development process of sub-micron to nano-scale focusing in recent years are introduced. When an X-ray focusing system approaches the diffraction limit, the wavefront distortion caused by the fabrication, mounting and collimation will seriously affect the final focusing performance of the system. Therefore, the related focused X-ray wavefront detection and manipulation play important roles as cutting-edge technologies and methods. In addition, the current main wavefront detection and manipulation techniques of the nanofocusing beam are introduced and compared, and the future development of X-ray diffraction-limited nanofocusing optics is also prospected.

This paper first reviews and comments on the performance of resolution and imaging efficiency of various types of X-ray lenses, and then discusses and predicts the roadmap of technical development of zone plate lenses in China, which was first established in 2013 by the author. Following the roadmap, the technical advance for the resolution from 70 nm up to 30 nm has been achieved by electron beam lithography with Au electroplating, based on the earlier success in 100 nm resolution zone plate lenses and convergent lenses for both soft and hard X-ray optics. When the resolution approaching 30 nm, the limitation to the aspect ratio (ratio of zone-height to zone-width) owing to the proximity effect in electron beam lithography becomes more and more severe. The commercial software packages, which are based on Monte Carlo model and development dynamics, are not able to manage the correction of proximity effect on the whole zone plate with the varying zone-widths from micrometers down to 30 nm. To overcome the difficulty, pattern correction of proximity effect is proposed in the electron beam lithography for 70 nm resolution zone plates and as high as 20∶1 for the aspect ratio has been realized. Furthermore, a local proximity effect correction is also developed in replicating 50 nm resolution zone plates and the aspect ratio of 15∶1 has been realized. In the attempt for 30 nm resolution zone plate lenses, pulsed Au electroplating is applied to eliminate the crystallization and epitaxial growth of Au, and 30 nm resolution zone plates for soft X ray are fabricated. For the characterizations of the fabricated zone plate lenses, high aspect ratio Siemens stars with various resolutions from 30 nm to 100 nm have been fabricated, which are used as standard samples for optical detection. 50 nm resolution imaging in both soft and hard X-ray has been demonstrated in Shanghai Synchrotron Radiation Facilities (SSRFs) for the first time in China by using completely in-house fabricated zone plate lenses.

Optics contamination has a great impact on X-ray transportation, especially in high-brightness, high-coherence X-ray free-electron lasers. However, there are very few related studies on the optics contamination of X-ray free-electron lasers. First, the characteristics of the X-ray free-electron laser are given. Then, the effects, control, and cleaning schemes of carbon contamination in synchrotron radiation are summarized. Moreover, the special effects of carbon contamination on the beam quality in X-ray free-electron laser beamlines are analyzed. Finally, the damage, melting, and blocking that particle contamination may occur on X-ray free-electron laser mirrors are analyzed, and the effects of the three conditions on the beam quality are given.

In the research of laser inertial confinement fusion (ICF), plasma diagnostics involving X-ray time, space and energy spectrum provides key experimental data for numerical simulation, and effectively promotes the understanding of key physical problems of ICF. The multi-channel grazing-incidence system represented by Kirkpatrick-Baez (KB) microscope is an important means to realize high-resolution X-ray spatial-temporal imaging, which has a wide range of applications in ICF diagnostics research. This paper mainly introduces the development history of high-resolution multi-channel KB imaging system, analyzes the bottleneck problems in the development of KB systems, and focuses on the domestic research progress in the development of multi-channel KB diagnosis system based on multilayer optics in recent years. With breakthroughs in key technologies such as precision thin-film devices and grazing-incidence X-ray optical integration, multi-channel multilayer KB microscope has been widely used in domestic ICF diagnostics, which effectively guarantees the development of relevant physical experiments.

X-ray diagnosis technology based on crystal diffraction is an important method to obtain key state parameters in the research fields of X-ray spectroscopy diagnosis, material analysis and structural characterization on high energy laser devices and synchrotron radiation devices. The calculation of crystal diffraction efficiency based on the dynamical diffraction theory and the design of spectrometer structure based on different focusing schemes are the two main interests in the research of the X-ray crystal spectrometer. In this paper, the evolution and latest progresses of classical crystal diffraction theory such as X-ray dynamical diffraction theory and diffraction calculation method for different crystal objects are summarized and discussed. The diffraction focusing characteristics, development, and application of X-ray crystal spectrometers with different geometries are discussed, and the X-ray crystal diffraction theory involved in the X-ray crystal spectrometer and the innovation and progresses of the focusing characteristics of various spectrometers, as well as the overall development trend, are comprehensively expounded.

This paper overviews the progress of the dynamic hohlraum (DH) related experimental research on an 8-MA facility during the last five years. The paper makes a conclusion to the research of the typical characteristic of the DH energetics, as well as a comparison with Z-facility. A detailed demonstration of the diagnostic method and results is given on the features of shock wave propagation and DH formation during wire-array implosion and interaction with the low-density foam. Some optimization processes for the DH load are reported. In the end, analysis and conclusion are conducted on experimental exploration of the DH driven capsule implosion.

The development status of vacuum-ultraviolet (VUV) solid-state 193-nm laser sources is reviewed in this paper, including the related nonlinear crystals (e.g., BBO, LBO, CLBO, KBBF) and their characteristics, the development of 193-nm band continuous solid-state laser and pulsed solid-state laser in recent tens of years, the combinations of fundamental lasers used for generation of 193-nm solid laser, and their merits and drawbacks. The two-photon absorption phenomenon is described, which has influence on the transmission of the nonlinear crystals and the output power of ultraviolet laser. The effect of laser induced contamination in deep ultraviolet lasers is discussed, and some possible ways to avoid or alleviate this effect are also given. Finally, the difficulties and challenges of realizing high repetition rate deep ultraviolet lasers are evaluated.

A hard X-ray imaging system with spherically bent crystal as transmission imaging device is proposed. Its basic structure is an isotropic X-ray point source and a Laue spherical transmission crystal. Different from the reflection configuration, it enables us to solve the problem in hard X-ray imaging with energy above 8 keV. In the imaging system, the X-ray is radiated by a small point source, is dispersed by a transmission grating placed in front of the spherically bent α-quartz crystal, is transmitted by the crystal, and finally is imaged on the detector surface behind the crystal. The imaging mechanism of spherical transmission crystal to obtain different magnification images is discussed, and the ray tracing program is used to design the transmission imaging system for simulation. The simulation results show that the proposed structure can achieve two-dimensional spatial resolution imaging. The backlight imaging experiment of X-ray tube with Cu target also proves that the experimental results are consistent with the theoretical analysis.

Spherically bent crystal imaging is a measurement technique that can be used to achieve quasi-monochromatic high-resolution imaging in experimental studies of inertial confinement fusion based on high power laser facilities. With a high-resolution backlight arrangement design similar to that of point projection, the spherically bent crystal imaging system developed is applied to 10 kJ-level Shenguang facilities for hydrodynamic instability, implosion compression trajectory, and other experimental studies of laser-induced plasmas. When it is applied to interface trajectory measurement during the ablation and compression of spherical samples, the spherically bent crystal imaging has the advantages of a large field of view, quasi-monochromaticity, and self-smoothing of backlight intensity distribution. The influences of the resolution in the meridian direction and that in the sagittal direction on one-dimensional interface trajectory measurement are balanced by optimizing imaging parameter design without changing the arrangement parameters of the imaging system. Even with a larger backlight, the spatial resolution of the interface trajectory absorption image is improved, and the signal-to-noise ratio of the image is also effectively enhanced. An accuracy of 2.1% is achieved in implosion velocity measurement by combining the optimized spherically bent crystal imaging system with the alternative target design.

Based on the experimental conditions of the Shenguang-100 kJ laser facility, the feasibility and applicability of the deep ultraviolet quintuple-frequency Thomson scattering diagnostics are evaluated, and compared with the widely used quadruple-frequency Thomson scattering, so as to provide a reference for the technical route for high-precision diagnosis of inertial confinement fusion plasmas. The probe beam signal, the drive-beam background, and the bremsstrahlung background are evaluated, and the measurement bands of the Thomson scattering ion spectrum and electron spectrum are discussed respectively. The results show that for the ion spectrum, the signal-to-background ratio can be significantly improved by using a quintuple-frequency probe beam. For the red peak of the electron spectrum, whether a quintuple-frequency probe beam or a quadruple-frequency probe beam is used, it is strongly disturbed by the intense background of the drive beam. For the blue peak of the electron spectrum, the drive beam background can be avoided by using a quintuple-frequency probe beam, while the bremsstrahlung background will be significantly enhanced. In general, quintuple-frequency Thomson scattering has significant advantages in the measurement of low atomic number plasmas, but not for high atomic number plasmas.

In the experimental study of inertial confinement fusion, the core detection element of the filter fluorescence spectrometer in quantitative diagnostic equipment for hard X-ray spectroscopy is the hard X-ray scintillation detector. In view of this, a method for calibrating the energy sensitivity of hard X-ray detectors based on semiconductor hard X-ray diodes is established, which has the advantages of fast and simple. The traceability of the quantity does not depend on the intensity of the radioactive source, and the calibration uncertainty is 7%. First, the proposed method is used to calibrate the energy sensitivity of sodium iodide and barium fluoride scintillation detectors in different energy sensitivity ranges on hard X-ray machine and Shanghai synchrotron radiation light source, respectively. Second, the theoretical sensitivity curves of the two types of detectors are calculated by using the Monte Carlo simulation program Geant4, and compared with the calibration experimental results, the calibration datasets are extrapolated to the whole energy range (10--100 keV). Finally, the proposed method can be applied to the precise calibration of energy transmittance of vacuum isolator, and the calibration results of low sensitive BaF2 scintillation detector can be applied to the experimental study of high brightness hard X-ray sources.

Extreme ultraviolet (XUV) comb is a newly developed coherent laser source in the extreme ultraviolet region. It has numerous applications not only in the field of precision spectroscopic measurement but also in strong field physics. The out-coupling methods for XUV comb are extremely crucial in building an XUV comb as they determine the out-coupling efficiency, light intensity, and spectral range of the comb. Based on a home-build XUV comb system, we use the Brewster plate and the self-designed micro-nano grating to out-couple the generated XUV light. With both methods, we can obtain harmonics with a power of microwatt level. Comparing the two methods, we can obtain higher harmonic power and better spatial structure with the micro-nano grating method, while it is easier to obtain, install, clean, and replace the Brewster plates. However, as a transmitting optical element, it introduces nonlinear effects and thus hinders the performance of the XUV comb setup. Our study provides important information for building an XUV comb setup with outstanding performance.

In this paper, we demonstrate the performance parameters and stability of the FEL-III beamline of Shanghai high repetition rate X-ray free electron laser and extreme light facility (SHINE). FEL-III beamline covers the photon energy of 10--25 keV, which is the FEL beamline with the highest energy among the initial three beamlines in SHINE. In the studies and analysis of performance parameters and stability of sources, the electron beam shot noise, the transverse position and incident angle jitter of the electron beam launch condition, and the horizontal position misplacement of the quadrupoles are taken into account. The results provide a solid and clear illustration for the possible performance and stability of the light source. It will also serve as a reference for the design of the optical beamlines and the experimental endstations, and it will provide reference for potential user experiments.

A resonant cavity system composed of a sapphire crystal as a Bragg mirror is designed to control the state of the X-ray pulse radiation beam to achieve stable propagation in an open cavity,and then form oscillation. Taking the open stable cavity system composed of two plane crystal Bragg mirrors as the model, the relationship between the focal length and the distance between the two lenses in the resonant cavity is obtained by calculating the transport matrix and analyzing the lateral stability condition of the radiation beam. The design parameters of the resonant cavity system are optimized to satisfy the gain maximization condition, i.e., the Rayleigh length ZR of the radiation beam matches the focusing parameter Zβ of the electron beam. The X-ray tracing software SHADOW is used to simulate the optical tracing. The simulation results show that the single-pass loss of the radiation beam in the entire resonant cavity system is less than 20%. Although different from the initial state, the state of the radiation beam after oscillating for one period in the resonant cavity is acceptable. The simulation results show that the optical design parameters of the resonant cavity system are feasible.

Based on design algorithms of hard X-ray spectrometers in advanced light sources around the world, high energy resolution is realized by adopting cylindrically bent Bragg crystals. A new structure of a double diffraction spectrometer is proposed, which can achieve 2×10 5 energy resolution of single pulse in the photon energy range of 3--25 keV. The energy resolution performance of the spectrometer is verified by theoretical analysis and numerical calculation. And a broad spectrum with bandwidth beyond 1% can be reconstructed via mechanical scan. This technique can potentially be used to measure the fine structure in self-amplified spontaneous emission (SASE) spectra within hard X-ray spectral range for Shanghai High Repetition Rate hard X-ray free electron laser (XFEL) and Extreme Light Facility (SHINE), and it can be applied to detection and application of the cutting edge user scientific researches demanding high resolving power, preserving important merit of value in science and technology.

A high-energy X-ray microfocal spot has an important application in high-energy microbeam X-ray analysis. To obtain a high-energy X-ray lens with a microfocal spot, a tapered monocapillary lens was designed in theory. This lens can focus X-ray with an energy of 100 keV onto a micron-scale focal spot with a gain in the focal spot diameter and power density of the order of microns and tens, respectively, and the corresponding focal length is ~5 mm. Furthermore, the characteristics of the lens with a glass and a gold reflecting surface were simulated in theory, respectively. The flux in the focal spot of this X-ray lens with a gold reflecting surface is 14.8 times that with a borosilicate glass surface. The simulation results are helpful in the fabrication and application of such tapered monocapillary X-ray lens.

The X-ray micro pore optic with sector (MPOS) is a new type of X-ray focusing device. Compared with the traditional micro pore focusing devices, MPOS has application prospects in space X-ray detection with the advantages of high integration and lightweight. The MPOS focusing device is designed and developed based on the focusing theorem. The roughness of the inner wall of the micro pore is 0.4--0.5 nm, and the precision of array distribution is about 5.5%. The focusing performance of the device is tested with a point-to-point X-ray test platform. The results show that the focal spot shape is a clear hexagonal star, and the angular resolution is 7.7'@1 keV with operating voltage of 5.0 kV and current of 0.1 mA.

The interaction of femtosecond laser with plasmas can produce ultrashort and brilliant extreme-ultraviolet (EUV) radiations, which can be applied in high-resolution imaging and time-resolved spectroscopy. To further improve the radiance, the high-efficiency generation of EUV radiations from carbon nanotube foam (CNF) targets irradiated by a relativistic femtosecond laser is demonstrated. The experimental result indicates that when the laser energy is 1.2 J and the CNF density is 4 mg/cm 3 , the single-shot EUV spectrum intensity is around 0.1 mJ·nm -1·sr -1. Compared with high-density solid targets, the low-density CNF targets can effectively improve laser absorptivity, and therefore realize an enhancement of EUV conversion efficiency by two orders of magnitudes. Furthermore, the EUV radiations from CNFs are quasi-continuum in the wavelength range of 15--30 nm, which is suitable for applications including ultrafast absorption spectroscopy.

The effect of initial pressure on the output characteristics of the 46.9 nm laser is investigated when the Ar-He mixture with a pressure ratio of 8∶1 is filled into the capillary. By measuring the pressure range of 46.9 nm laser produced by Ar-He mixture, and the corresponding laser intensity and spot shape information at each pressure, the relationship between laser output characteristics and initial pressure of Ar-He mixture is summarized. Then, the influence of the initial pressure of Ar-He mixture on the laser spot is analyzed from the point of view of the plasma column, and the reason for the change of the output characteristics of 46.9 nm laser caused by the initial pressure of the Ar-He mixture is obtained. The above research on the laser characteristics is beneficial to improve the laser amplitude and change the shape of the laser spot.

Conventional micro-computed tomography (micro-CT) with high spatial resolution faces the dilemma of a small field of view. In recent years, an electron-beam micro-CT (EBMCT) with a wide field of view has been proposed, which is based on the electron-beam deflection for scanning and multi-microfocus X-ray sources. It can not only maintain the advantage of high spatial resolution, but also greatly expand the field of view of CT scanning and the size of inspectable samples. However, due to the special multi-focus array scanning mode of EBMCT, its projection data encounter both truncation and redundancy. EBMCT generally uses an iterative image reconstruction algorithm that has a low requirement for projection data, but the algorithm requires massive computations and long reconstruction time because the projection data of array focuses are huge, and it is difficult to meet the demand for fast CT scanning and detection by EBMCT. In this paper, a smooth weighted multi-source filtered back-projection (MSFBP) algorithm is proposed. Simulation and experimental results show that the proposed algorithm eliminates artifacts caused by the redundancy of projection data and effectively suppresses truncation artifacts. The quality indicators of reconstructed images, including the root-mean-square error, peak signal-to-noise ratio, structural similarity, and spatial resolution, outperform those of traditional image reconstruction algorithms such as rebinning. Under the same conditions of computer hardware and image matrices, the reconstruction speed of the proposed algorithm is more than 3.3 times faster than that of the simultaneous algebraic reconstruction technique, which lays a good foundation for the application of the EBMCT system in the fast and wide field of view CT detection.

For the problem that computer tomography (CT) images after denoising by the non-local mean algorithm cause edge fog and the disappearance of small feature information, an adaptive non-local mean denoising method based on feature fusion is proposed. Firstly, the similarity judgment of the center pixel is carried out to exclude the effect of non-similar pixels on the denoising effect. Then a Gaussian weighting method based on feature fusion is proposed, considering the self-similarity of images from the maximum eigenvalue of similar frame matrix and Euclidean distance between pixels. Finally, the supremum and infimum of the adaptive filter coefficient are constrained based on the structure tensor, which solves the problem that image quality is affected when the infimum of filter coefficient is zero. Simulations and practical applications prove that the proposed algorithm has better edge protection and detail information effect. The proposed algorithm improves the structure similarity by about 4% on average, and the peak signal to noise ratio increases by nearly 4 dB on average, compared with the non-local mean algorithm.

Aiming at large field of view and high-resolution microfocus computed tomography (micro-CT), a source translation based CT (STCT) imaging method is proposed. This scanning method adopts the simultaneous iterative reconstruction algorithm based on the minimization of image total variation (SIRT-TV), which has problems such as long image reconstruction time and large amount of calculation. The ramp filter is divided and based on the properties of Fourier transform to derive a STCT analytical reconstruction algorithm (STCT-DHB) based on derivative-Hilbert transform-back projection (DHB). Simulation and practical experiment results show that the STCT-DHB algorithm can effectively suppress high-frequency noise of the image, and improve the efficiency of image reconstruction while maintaining the quality of the reconstructed image.