Abstract.We have developed a diffraction enhanced imaging (DEI) system at beamline BL07 at the SAGA Light Source. BL07 is a beamline for using high energy X-rays up to 35 keV generated from a superconducting wiggler placed in the straight section of the storage ring. The DEI measurement system is composed of a Si(220) asymmetric crystal for expanding the beam, a Si(220) crystal analyser, and a high-resolution CCD camera. We demonstrated the observation of a rope recovered from the ruins of the Mietsu Navy in Japan.
IntroductionTraditional X-ray imaging is a powerful tool to observe the internal structure of materials, but is not sufficiently sensitive for materials that consist of light elements because their absorption effects are excessively weak and do not produce a clear contrast. Phase imaging, which uses the phase shift of Xrays in materials to produce an image contrast, is an innovative technique used to solve this problem. The cross section of a phase shift is about 1000 times larger than an absorption cross section, which enables us to observe the structure of soft materials such as bio-materials or polymers. Compared to several other phase imaging methods that use a crystal interferometer [1-3], propagation-based phase imaging [4], and X-ray Talbot interferometry [5,6], diffraction enhanced imaging (DEI) has advantages such as a wide dynamic range of the material density and a simple experimental arrangement [7][8][9]. In the DEI method, refraction angles of X-rays penetrating materials are analyzed by a crystal analyzer.The SAGA Light Source has started operation in 2006 with three beamlines. In the initial stage of our development, we had developed the DEI system at BL15, which uses a bending magnet as a light source. We used X-rays at energy of 14 keV, however, this X-ray energy was not sufficiently high to enable the application of DEI to dense or thick specimens. In the recent years, we have constructed an additional beamline, called BL07, with a superconducting wiggler as a light source. It can produce Xrays with the energies of up to 35 keV, making it suitable for use with the DEI method. Hence, we developed a DEI measurement system for BL07 to perform the structural investigations of soft materials.