Abstract
Wide-angle incident X-ray waveguide making use of surface diffraction has recently been proved feasible. This thesis reports on the possibility of using Y-shaped waveguides for X-ray beam splitting at wide-angle incidence. The main function of this splitting waveguide is to change the direction of X-ray beam when propagating in the waveguide, and to divide the incident beam into two bunches. The preparation of the splitting waveguides involves etching a rectangular waveguide on a silicon wafer. The waveguide is then coated with gold thin films. The angle of beam splitting is about 0.3°, relative to the incident beam. This angle is smaller than the critical angle of the total external reflection from the interface of silicon and gold. Therefore, the power loss due to change of the direction of the X-rays is negligibly small. The theoretical calculation of this wave-guiding effect due to diffraction is based on Maxwell’s equations, where the mode of electromagnetic wave-propagating in the waveguide is considered. When a mode is not allowed as a TE or a TM mode, then the mode can be expressed as the superposition of the allowed TE or TM modes. Consequently, the intensity of electromagnetic wave oscillates. Also, because the angle of splitting is very small, the difference between TE and TM mode is almost undetectable. The experiment is carried out at the National Synchrotron Radiation Center (NSRRC). An 8-circle diffractometer is used to perform the (113) surface diffraction with the photon energies close to 8.878 keV. Wave guiding effects and beam slitting are observed. Detailed analysis of the degree of beam splitting is also reported.