Successful development of an x-ray microscope with high sensitivity and spatial resolution

Mar 4, 2013

Under the leadership of TAKAHASHI Yukio , Associate Professor, Graduate School of Engineering, Osaka University and ISHIKAWA Tetsuya , Director, SPring-8 Center Harima Institute, Riken, a group of researchers succeeded in developing an x-ray microscope with high sensitivity and spatial resolution.
By measuring phase shift when x-ray pass through an object, even an object with small absorption can be visualized, which is called Phase Contrast Imaging. In the Beamline BL29XUL at the synchrotron radiation facility SPring-8, Department of Physical Sciences I, Riken, this group of researchers developed a new phase contrast imaging method called "x-ray ptychography" equipped with an illumination optical system with an x-ray collector mirror and a spatial filter. This x-ray ptychography succeeded in visualizing a small phase shift of about x-ray wavelength of ( - λ /320) with a high spatial resolution of about 10nm.
This microscope is helpful in observing, especially, biological soft tissues consisting of light elements with low x-ray absorption and this group's achievement will lead to the possible applications to bio-imaging using SPring-8. Also in coherent x-ray diffractive imaging experiments at SACLA (SPring-8 Angstrom Compact free electron laser), similar optical systems are used. By irradiating an x-ray laser with the high photon density of SACLA, a high-resolution and high-sensitivity x-ray phase-contrast imaging becomes available.

We demonstrate high-resolution and high-sensitivity x-ray phase-contrast imaging of a weakly scattering extended object by scanning coherent diffractive imaging, i.e., ptychography, using a focused x-ray beam with a spatial filter. We develop the x-ray illumination optics installed with the spatial filter to collect coherent diffraction patterns with a high signal-to-noise ratio. We quantitatively visualize the object with a slight phase shift ( ∼ λ/320) at spatial resolution better than 17 nm in a field of view larger than ∼ 2×2μm2. The present coherent method has a marked potential for high-resolution and wide-field-of-view observation of weakly scattering objects such as biological soft tissues.

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To learn more about this research, please read the full research report entitled " High-resolution and high-sensitivity phase-contrast imaging by focused hard x-ray ptychography with a spatial filter " at this page of the Applied Physics Letters website.

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