Subsub-Arcseconds X-Ray Imaging With Multi-Image X-Ray Interferometer Module (Mixim): Experimental Results

We have proposed a new style X-ray interferometer, Multi-Image X-ray Interferometer Module (MIXIM), to achieve high angular resolution. MIXIM is comprised of a grating and an X-ray detector, and its angular resolution is in inverse proportion to the distance between two components. Although we have already detected a 1D interference fringe which corresponds an angular resolution of about 1 '' in our past experiment, its amplitude is not so high partly because of the lack of the spatial resolution of the X-ray detector. Then we newly adopt a CMOS detector which has both high spatial resolution (<2.5 mu m) and high spectroscopic capability (FWHM similar to 170 eV @5:9 keV) and evaluate the performance of MIXIM at BL20B2 in SPring-8, the synchrotron radiation facility in Japan. 1D interference fringes in this experiment have much higher amplitudes than those in the past experiment, which demonstrates the improvement of the performance due to the new CMOS detector. We also introduce a 2D grating for the first time, and try to obtain the 2D profile of the X-ray beam of which the size is 0.28 '' (H) and 0.06 '' (V). Extending the distance between two components to 866:5 cm, 2D imaging by MIXIM succeeds in capturing the horizontally elongated beam structure. The angular resolution at this configuration is calculated to be 0.076 '', which is the highest ever achieved for astronomical X-ray imagers.