A two-crystal X-ray interferometer

Zeitschrift für Physik A Hadrons and nuclei - The construction and successful operation of an X-ray interferometer consisting of twoseparate crystals is described. Alignment is made with the...     

A three-beam case X-ray interferometer

A new type of X-ray interferometer is described in which total reflection is established in the process of beam splitting, beam deflection and beam recombination by making essential use of simultaneous Bragg case diffraction from two different sets of net planes.The amplitudes of the interfering beams are calculated along the lines of the dynamical theory of X-ray diffraction. It is found that in the general non-planar three-beam case a complicated interaction of polarization states occurs which results in a destruction of interference contrast. On the other hand, in the planar case the polarization states stay separated and interference contrast can reach 100%.A monolithic interferometer using coplanar (440) and (404) reflections was made from a perfect silicon crystal and operated successfully. The degree of interference contrast was investigated experimentally with NiK radiation of an ordinary X-ray tube and with synchrotron X-rays from DESY.Focusing requirements and source properties influencing the coherence conditions are discussed.Part of doctorate thesis (University of Dortmund, 1976)     

High-resolution,quasi-Fabry—Perot X-ray interferometer

An extremely simple X-ray interferometer is described that should provide resolutions (λ/Δλ) of more than 10⁵. It relies on the use of nonlocalized, quasi-Fabry—Pérot interference fringes, which are detectable when a widely divergent beam of X-rays from a point source is incident on a good quality crystal. The crystal has to have a suitable lattice spacing, and in the basic method described, must not exceed a certain thickness (or coherence length).     

X-ray interferometer based on fresnel zone plates

A new type of X-ray interferometer based on three multilevel zone plates with common lens axis is suggested. Like to well-known triple Laue-case X-ray interferometer this interferometer does not impose strict requirements on the spatial and time coherence of the incident wave and therefore can be used with laboratory X-ray sources. The interferometer has advantages in the area of phase-contrast X-ray imaging connected with the image magnification.     

Eikonal approximation in the theory of X-ray interferometer

On the basis of eikonal approximation a theory of X-ray moiré formation is presented in the case where deformations are present in all three plates of the interferometer. The role of each plate of the interferometer in the process of moiré formation is revealed. The theory can be applied for the general case of weak deformations.     

An X-ray interferometer with Bragg case beam splitting and beam recombination

A new type of X-ray interferometer which uses Bragg case transmission for beam splitting and for beam recombination is described. The principles and special problems of this interferometer are discussed and a strict plane-wave treatment of the interference phenomena is presented. The feasibility of such a device is demonstrated by some interference patterns, obtained with an instrument made from a silicon crystal for use with copperKα radiation and the 220 Bragg reflection. Since, for the operation of the Bragg case interferometer, strong absorption is not essential, such devices may also be more suitable than the previously reported Laue case interferometer^1,2 for use with neutrons.     

X-ray phase contrast imaging based on three-block multilevel zone plate interferometer

A new scheme of X-ray phase contrast imaging, based on the previously suggested three-block interferometer composed by multilevel Fresnel zone plates, is considered. Two significant features, namely, image optical magnification and low requirements on the spatial and temporal coherency of incident radiation are combined in this scheme.     

X-ray phase-sensitive microscope imaging with a grating interferometer: Theory and simulation

A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer, which simultaneously enables the high spatial resolution imaging and the improved image contrast. By using this theory, several key parameters of phase contrast imaging can be predicted, for instance, the fringe visibility and period, and the conversion condition from the differential phase imaging (DPI) to the phase difference imaging (PDI). Additionally, numerical simulations are performed with certain x-ray optical components and imaging geometry. Comparison with the available experimental measurement [Appl. Phys. Lett. 113 063105 (2018)] demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.     

Two-dimensional interferogram of an exploding selenium foil using asoft X-ray laser interferometer

We have developed a soft X-ray interferometer capable of probing large high-density plasmas with micron spatial resolutions. A neon-like yttrium X-ray laser operating at 155 Å was combined with the Mach-Zehnder interferometer to obtain electron density profiles of a laser-produced exploding selenium foil plasma. The plasma was produced with one Nova laser beam using a 120-μm line focus, the same conditions used to create a selenium X-ray laser. The interferogram of the selenium plasma was obtained from an end-on perspective     

The quantum stellar interferometer

In this paper we propose a new interferometric scheme using photon entanglement. The two main limitations of stellar interferometry are (a) the small sensitivity and (b) the need for long delay-lines to compensate the path difference between the telescopes during observing runs. Entangled-photon pairs, generated by spontaneous parametric down-conversion, open the way to measuring quantum states correlation in the near infrared between two spatially separated telescopes and at very high sensitivities (down to a few stellar photons), thanks to a new interferometric layout which does not make use of complex long delay-lines. A femtosecond laser coupled to a nonlinear crystal is used as a local oscillator to perform the double homodyne measurements. This new quantum interferometer allows to measure astronomical objet sizes with very high angular resolution down to μas level.     

用X射线激光M-Z干涉仪诊断点聚焦CH等离子体电子密度

在神光Ⅱ装置上，用软X射线激光Mach-Zehnder干涉仪诊断了点聚焦CH等离子体电子密度N_e分布，介绍了实验结果. 通过Abel变换进行了密度反演， 给出了N_e的2D分布，测得的最高N_e为3.2×10²¹cm^-3. 通过同1.5维JB19程序以及二维XRL2D程序的模拟结果的比较，发现高密度区，限流因子取0.05的理论结果同实验相符，但是低密度区实验得到的N_e分布下降得更快，而且理论模拟的N_e二维分布同实验结果在细节上有比较大的差别. 粗略的误差分析显示，干涉仪面型误差是实验误差的主要来源. 关键词： 类镍银X射线激光 Mach-Zehnder干涉仪 密度反演 Abel变换     

The use of defocussed position of a Ronchi grating for evaluating the refractive index of lens

This report describes a Ronchi-grating shearing interferometric collimation method for determining the refractive index of a lens. A new formula has been deduced for the refractive index of the lens, which is independent of lens parameters. This newly developed device has two lenses. One of them collimates the light from a point source while the other acts as a decollimator. The point source acting as a test target is situated in the front focal plane of the collimator. The test lens is placed inside a glass cell in the back focal plane of the collimator. The Ronchi grating is exactly placed in the back focal plane of the decollimator, and a fringe-free space is observed in the common region. When the test lens is immersed in a liquid cell, it disturbs the focal point and hence interference fringes are observed. The combined system consisting of the test lens and the decollimator is moved to bring the focal point on the Ronchi grating. Thus, the difference between the two settings gives the amount of defocusing.     

X-ray phase contrast imaging with optical magnification using three-block interferometer with bi-level Fresnel zone plates

The possibility of X-ray phase contrast imaging using already suggested three-block interferometer consisting of bi-level Fresnel zone plates is considered. The interferometer operates in the amplitude-division mode and does not impose strong requirements to spatial and temporal coherences of an initial radiation. The use of the Fresnel zone plates as the interferometer blocks allows one to obtain an optically magnified image of an object and to condense the radiation incident on the tested object.     

Using a plane wave approximation in simulation of radiation distribution in an X-ray Talbot interferometer

This study is devoted to the analysis of the plane-wave approximation applicability to X-ray radiation incident on an object. Based on simple calculations, it is shown that an X-ray tube focal spot 0.4 × 0.8 mm in size at distances of ~1 m can be considered as a point source; however, the plane-wave approximation for such X-ray radiation with energy E = 22keV is valid for radiation source–object distances much longer than 10 m.     

13.9 nm马赫贞德干涉仪用软X射线分束镜研究

 介绍了13.9 nm马赫贞德干涉仪用软X射线分束镜的设计、制备与性能检测。基于分束镜反射率和透过率乘积最大的评价标准,设计了13.9 nm软X射线激光干涉实验用多层膜分束镜。采用磁控溅射方法在有效面积为10 mm×10 mm、厚度为100 nm的Si3N4基底上镀制了Mo/Si多层膜,制成了多层膜分束镜。利用X射线掠入射衍射的方法测量了Mo/Si多层膜的周期。用扩束He-Ne激光束进行的投影成像方法定性分析了分束镜的面形精度,利用光学轮廓仪完成了分束镜面形精确测量。利用北京同步辐射装置测量了分束镜反射率和透射率,在13.9 nm处,分束镜反射率和透过率乘积达4%。使用多层膜分束镜构建了软X射线马赫贞德干涉仪,并应用于13.9 nm软X射线激光干涉实验中,获得了清晰的含有C8H8等离子体电子密度信息的动态干涉条纹。     

13.9 nm马赫贞德干涉仪用软X射线分束镜研究

介绍了13.9 nm马赫贞德干涉仪用软X射线分束镜的设计、制备与性能检测。基于分束镜反射率和透过率乘积最大的评价标准,设计了13.9 nm软X射线激光干涉实验用多层膜分束镜。采用磁控溅射方法在有效面积为10 mm×10 mm、厚度为100 nm的Si3N4基底上镀制了Mo/Si多层膜,制成了多层膜分束镜。利用X射线掠入射衍射的方法测量了Mo/Si多层膜的周期。用扩束He-Ne激光束进行的投影成像方法定性分析了分束镜的面形精度,利用光学轮廓仪完成了分束镜面形精确测量。利用北京同步辐射装置测量了分束镜反射率和透射率,在13.9 nm处,分束镜反射率和透过率乘积达4%。使用多层膜分束镜构建了软X射线马赫贞德干涉仪,并应用于13.9 nm软X射线激光干涉实验中,获得了清晰的含有C8H8等离子体电子密度信息的动态干涉条纹。     

X-ray submicrometer phase contrast imaging with a Fresnel zone plate and a two dimensional grating interferometer

The application of a two dimensional (2D) grating interferometer-Fresnel zone plate combination for quantitative submicron phase contrast imaging is reported. The combination of the two optical elements allows quick recovery of the phase shift introduced by a sample in a hard X-ray beam, avoiding artifacts observed when using the one dimensional (1D) interferometer for a sample with features oriented in the unsensitive direction of the interferometer. The setup provides submicron resolution due to the optics magnification ratio and a fine sensitivity in both transverse orientations due to the 2D analysis gratings. The method opens up possibilities for sub-micro phase contrast tomography of microscopic objects made of light and/or homogeneous materials with randomly oriented features.     

Theory of an X-ray interferometer in the form of an array of planar compound refractive lenses

The results of theoretical analysis of the interference pattern created by an X-ray multilens interferometer in the case of an arbitrary number of planar compound refractive lenses are presented. The full widths at half maximum of the resonance peaks in the transverse and longitudinal directions relative to the direction of synchrotron radiation are calculated at distances corresponding to the fractional Talbot effect. A relation between the widths is shown to exist that is very close to the width relation in the case of focusing by a single lens. A difference between the fractional and full Talbot effects is discussed, and the necessary conditions for the transverse and longitudinal coherence of radiation are analyzed, the satisfaction of which guarantees that undistorted interference peaks will be observed experimentally.     

The GI2T/REGAIN interferometer

After five years of development, the REGAIN project has obtained its first light during summer 1999. The main goals were improving the quality and quantity of data through a complete re-designing and re-building of the central beam combiner. The REGAIN interferometric bonnette delivers two coherent foci, one at visible wavelengths and one in the IR bands (J, H and K). The visible focus is equipped with a dedicated visible spectrograph and two photon counting detectors. The infrared focus can be equipped with different instruments. The main technical issues that have been chosen will be discussed here.