New Methods And Technologies Of Synchrotron Radiation Based X-ray Microscopy

X-ray has been widely used in the field of imaging science ever since it was discovered by Wilhelm Conrad Rontgen in1895. The properties of short wavelength and high penetration make X-ray filling the gap between optical microscope and electron microscope by providing both high spatial resolution and large field of view at the same time. The development of synchrotron radiation source brings a breakthrough to X-ray microscopy, many new X-ray microscopy techniques become possible thanks to the properties of high brightness, high throughput and high collimation of synchrotron radiation source. Recently, scientists have invented lots of new microscopy techniques and theories based on synchrotron radiation, such as Coherent Diffraction Imaging (CDI), X-ray PhotoEmission Electron Microscope (XPEEM), X-ray holography, X-ray fluorescence microscopy (XFM) and so on.In this thesis, we summarized common used X-ray microscopies based on synchrotron radiation by introducing their frameworks, imaging characteristics, applied fields and so on.Most importantly, we presented three new theories and methods of synchrotron based X-ray microscopies.1. We presented a new X-ray microscopy technique based on structured illumination in a microscope that characterizes the size of the sub-resolution-limit features, and we named it structured dark-field imaging (SDFI). The technique is effective for characterizing fine structures substantially beyond the Rayleigh resolution of the microscope. We carried out optical experiments to demonstrate the basic principle of this new technique. Experimental results show good agreement with theoretical predictions. This technique will find a wide range of important imaging applications with feature size down to nanometer scale, such as oil and gas reservoir rocks, advanced composites and functional nano-devices and materials.2. We developed an element-specific X-ray microscopy method by using Zernike phase contrast images near absorption edges, where the real part of the refractive index experiences a sudden change. In this method, two phase contrast images, one at the edge of the target element and another beside the edge, are subtracted to enhance the signal of the element. Numerical simulation experiments and signal to noise ratio analysis showed that the X-ray exposure required by this method is significantly lower than conventional absorption-based elemental sensitive Transmission X-ray Microscopy (TXM) imaging method. The new technique would be promising for imaging samples extremely sensitive to the exposure of X-ray.3. We invented a new kind of phase zone plate, which is able to improve the diffraction efficiency without thicken the zone height by replacing blank parts of ZP with another metal, of which the phase shift is negative at working energy. We name this new kind of ZP the Positive and Negative Phase Zone Plate (PNPZP). In this thesis, we explained the basic theory, calculated the diffraction efficiency and introduced manufacture methods of PNPZP.