Development and its medical/biological application of a projection X-ray microscope using synchrotron radiation.

利用同步辐射作为光源的软x射线投影显微术已经发展起来。该系统由最外宽80nm的菲涅耳带片、0.5 ~ 20μmφ的针孔、标本架上的标本和背照CCD相机组成。在一些实验中，在带板的上游放置一个预针孔（10-100μmφ），对其进行相干照明。利用十纳米精度的压电驱动台阶实现了针孔的对准。在日本筑波光子工厂的BL-12A和BL-11A光束线上获得了波长为1.5nm、2.4nm和3.6nm的单色软x射线。从确定宽度的线与空间组成的测试图的线间距分辨率来看，10μmφ的预孔和1μmφ的针孔组合的空间分辨率最高，为0.2 ~ 0.3μm。通过该系统，我们获得了em网格，干燥的哺乳动物细胞和干燥的人类染色体的图像。哺乳动物细胞的颗粒结构和染色体的精细结构被区分开来。在图像采集的同时，进行了计算研究，1)评估带片与针孔组合的光学特性，2)研究了改善菲涅耳衍射畸变图像恢复质量的方法。该系统的进一步改进包括：1)分辨率的提高，2)湿环境下生物标本成像的发展，3)通过计算机处理提高图像质量，其医学/生物学应用有待研究。

Soft X-ray projection microscopy using synchrotron radiation as a light source has been developed. The system consists of a Fresnel zone plate with an outermost zone width of 80nm, a pinhole (0.5-20μmφ), specimens on a specimen holder, and a back-illuminated CCD camera. In some experiments, a pre-pinhole (10-100μmφ) was placed in the upper stream of the zone plate to give coherent illumination to it. The alignment of the pinhole was achieved with the aid of piezo-driven stages with ten-nanometer precision. Monochromatic soft X-rays of the wavelengths of 1.5nm, 2.4nm and 3.6nm were obtained from the beamline BL-12A and BL-11A at the Photon Factory, Tsukuba, Japan. The highest spatial resolution of 0.2-0.3μm was attained with the combination of a 10μmφ prepinhole and a 1μmφ pinhole, judging from the resolution of line spacing on a test pattern consisting of lines and spaces with defined widths. With this system, we obtained images of EM-grids, dried mammalian cells, and dried human chromosomes. Granular structure in mammalian cells and fine structure in chromosomes were distinguished. In parallel with the image acquisition, computational studies were conducted 1) to evaluate optical properties of the combination of a zone plate and a pinhole, and 2) to develop the method for the improvement of the quality of images recovered from the experimentally obtained images distorted by the Fresnel diffraction. Further improvements of the system in 1) the improvement of the resolution, 2) the development for imaging biological specimens in wet environment and 3) the improvement of the quality of images by a computer processing, and its medical/biological application remained to be studied.