[en] Two phase contrast imaging techniques, namely two dimensional grating interferometry and X-ray speckle tracking (XST), have been combined with the use of a Fresnel Zone Plate (FZP) for application to X-ray microscopy. Both techniques allows the phase shift introduced by a sample on a hard X-ray beam in two dimensions, to be recovered with a high sensitivity and low requirements on transverse and longitudinal coherence. Sub-micron phase imaging of carbon fibres was achieved using the two methods thanks to the high magnification ratio of the FZP. Advantages, drawbacks and differences between these two techniques for X-ray microscopy are discussed

[en] The grating-based shearing interferometer has been established and further developed on B16 at Diamond Light Source. The beamline performances of both an X-ray plane mirror and a compound refractive lens (CRL) have been investigated using this technique. The slope error of the X-ray mirror was retrieved from the wavefront phase gradient, which was measured using two different processing schemes: phase stepping and moiré fringe analysis. The interferometer has demonstrated a high sensitivity with sub-microradian accuracy. Some of the advantages, disadvantages and limitations for the two approaches will also be presented.

[en] X-ray active mirrors, such as bimorph and mechanically bendable mirrors, are increasingly being used on beamlines at modern synchrotron source facilities to generate either focused or “tophat” beams. As well as optical tests in the metrology lab, it is becoming increasingly important to optimise and characterise active optics under actual beamline operating conditions. Recently developed X-ray speckle-based at-wavelength metrology technique has shown great potential. The technique has been established and further developed at the Diamond Light Source and is increasingly being used to optimise active mirrors. Details of the X-ray speckle-based at-wavelength metrology technique and an example of its applicability in characterising and optimising a micro-focusing bimorph X-ray mirror are presented. Importantly, an unprecedented angular sensitivity in the range of two nanoradians for measuring the slope error of an optical surface has been demonstrated. Such a super precision metrology technique will be beneficial to the manufacturers of polished mirrors and also in optimization of beam shaping during experiments.

[en] X-ray dark-field contrast tomography can provide important supplementary information inside a sample to the conventional absorption tomography. Recently, the X-ray speckle based technique has been proposed to provide qualitative two-dimensional dark-field imaging with a simple experimental arrangement. In this letter, we deduce a relationship between the second moment of scattering angle distribution and cross-correlation degradation of speckle and establish a quantitative basis of X-ray dark-field tomography using single directional speckle scanning technique. In addition, the phase contrast images can be simultaneously retrieved permitting tomographic reconstruction, which yields enhanced contrast in weakly absorbing materials. Such complementary tomography technique can allow systematic investigation of complex samples containing both soft and hard materials.

[en] The optical responses of two sides of float glass in the soft-x-ray region were studied at the Indus-1 synchrotron facility. To the best of our knowledge these are the first experimentally obtained optical data for both sides of float glass in the soft-x-ray region. Optical constants δ and β were determined by use of angle-dependent reflectance techniques in the wavelength range 80-200 A. On the side of the glass that was tin indiffused, a significant difference in δ value from that of the non-tin-side surface was observed. The measured data were compared with Henke's tabulated value of SiO2. The surface roughness of float glass was separately determined by hard-x-ray reflectivity to minimize the number of fitting variables. The effect of a contamination layer on the determination of optical constants was avoided by an appropriate sample-cleaning method

[en] A portable device, using the speckle scanning technique, has been developed for in situ metrology of X-ray mirrors at synchrotron light facilities. A portable device for in situ metrology of synchrotron X-ray mirrors based on the near-field speckle scanning technique has been developed. Ultra-high angular sensitivity is achieved by scanning a piece of abrasive paper or filter membrane in the X-ray beam. In addition to the compact setup and ease of implementation, a user-friendly graphical user interface has been developed to ensure that optimizing active X-ray mirrors is simple and fast. The functionality and feasibility of this device have been demonstrated by characterizing and optimizing X-ray mirrors.

[en] The Beryl and YB66 crystals are proved to be suitable as analyzers in the energy range from 1.0keV to 2.0keV. The s-component reflectivity (Rs) of Beryl crystal reaches up to 10% with polarizing power Rs/Rp over 1000 at 1.1keV. The free-standing W/B4C multilayer has the phase shift over 5° with moderate transmission up to 1.7keV. The Bragg resonance width of the Beryl crystal is only 350 microradians at 1.1keV, and the incidence angle of the beam onto the crystal needs to be constant within 50 microradians or better. A high-precision polarimeter was used for the polarimetry experiment, and the complete polarization analysis of the APPLE II undulator at 1.1 keV and 1.56keV will be presented.

[en] A one dimensional (1D) compound refractive lens (CRL) has been characterized using the grating based rotating shearing interferometer technique. The method is based on the calculation of moiré fringes orientation to sense wavefront information. The phase shift and the optical aberration introduced by the 1D CRL on an X-ray beam were retrieved from a single moiré fringe image. The radius of curvature of the lens at the apex was derived. This physical radius of the CRL, which is also closely related to the focal length of the 1D CRL, was shown to vary with the incident angle of the incoming X-ray beam onto the CRL. The experimental measurement agreed very well with the theoretical expectations.

[en] The two-dimensional slope error of an X-ray mirror has been retrieved by employing the speckle scanning technique, which will be valuable at synchrotron radiation facilities and in astronomical telescopes. In situ metrology overcomes many of the limitations of existing metrology techniques and is capable of exceeding the performance of present-day optics. A novel technique for precisely characterizing an X-ray bimorph mirror and deducing its two-dimensional (2D) slope error map is presented. This technique has also been used to perform fast optimization of a bimorph mirror using the derived 2D piezo response functions. The measured focused beam size was significantly reduced after the optimization, and the slope error map was then verified by using geometrical optics to simulate the focused beam profile. This proposed technique is expected to be valuable for in situ metrology of X-ray mirrors at synchrotron radiation facilities and in astronomical telescopes

[en] Complete polarization analysis of the photon beam produced by a dual APPLE-II undulator configuration using a multilayer-based soft X-ray polarimeter is given. The use of an APPLE II undulator is extremely important for providing a high-brilliance X-ray beam with the capability to switch between various photon beam polarization states. A high-precision soft X-ray polarimeter has been used to systematically investigate the polarization characteristics of the two helical APPLE II undulators installed on beamline I06 at Diamond Light Source. A simple data acquisition and processing procedure has been developed to determine the Stokes polarization parameters for light polarized at arbitrary linear angles emitted from a single undulator, and for circularly polarized light emitted from both undulators in conjunction with a single-period undulator phasing unit. The purity of linear polarization is found to deteriorate as the polarization angle moves away from the horizontal and vertical modes. Importantly, a negative correlation between the degree of circular polarization and the photon flux has been found when the phasing unit is used