For modern synchrotron light sources, the push toward diffraction-limited and coherence-preserved beams demands accurate metrology on X-ray optics. Moreover, it is important to perform in-situ characterization and optimization of X-ray mirrors since their ultimate performance is critically dependent on the working conditions. Therefore, it is highly desirable to develop a portable metrology device, which can be easily implemented on a range of beamlines for in-situ metrology. An X-ray speckle-based portable device for in-situ metrology of synchrotron X-ray mirrors has been developed at Diamond Light Source. Ultra-high angular sensitivity is achieved by scanning the speckle generator 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 characterization and alignment of X-ray mirrors is simple and fast. The functionality and feasibility of this device is presented with representative examples.
To achieve high resolution and sensitivity on the nanometer scale, further development of X-ray optics is required. Although ex-situ metrology provides valuable information about X-ray optics, the ultimate performance of X-ray optics is critically dependent on the exact nature of the working conditions. Therefore, it is equally important to perform in-situ metrology at the optics’ operating wavelength (‘at-wavelength’ metrology) to optimize the performance of X-ray optics and correct and minimize the collective distortions of the upstream beamline optics, e.g. monochromator, windows, etc. Speckle-based technique has been implemented and further improved at Diamond Light Source. We have demonstrated that the angular sensitivity for measuring the slope error of an optical surface can reach an accuracy of two nanoradians. The recent development of the speckle-based at-wavelength metrology techniques will be presented. Representative examples of the applications of the speckle-based technique will also be given – including optimization of X-ray mirrors and characterization of compound refraction lenses. Such a high-precision metrology technique will be extremely beneficial for the manufacture and in-situ alignment/optimization of X-ray mirrors for next-generation synchrotron beamlines.
X-ray phase-contrast imaging has been developed as an alternative to conventional absorption imaging, partly for its
dose advantage over absorption imaging at high resolution. Grating-based imaging (GBI) and propagation-based
imaging (PBI) are two phase-contrast techniques used with polychromatic laboratory sources. We compare the two
methods by experiments and simulations with respect to required dose. A simulation method based on the projection
approximation is designed and verified with experiments. A comparison based on simulations of the doses required for
detection of an object with respect to its diameter is presented, showing that for monochromatic radiation, there is a dose
advantage for PBI for small features but an advantage for GBI at larger features. However, GBI suffers more from the
introduction of polychromatic radiation, in this case so much that PBI gives lower dose for all investigated feature sizes.
Furthermore, we present and compare experimental images of biomedical samples. While those support the dose
advantage of PBI, they also highlight the GBI advantage of quantitative reconstruction of multimaterial samples. For all
experiments a liquid-metal-jet source was used. Liquid-metal-jet sources are a promising option for laboratory-based
phase-contrast imaging due to the relatively high brightness and small spot size.