Development of a Wolter mirror soft X-ray phase contrast microscope for the observation of biological fine structure

用于观察生物样品微结构的软X射线相差显微镜的研制。(1)高分辨率高倍率光学系统的构建。我们设计并制作了高倍率光学系统，以获得高分辨率图像的实时图像。为了在大倍率下缩短光学系统，我们提出了一种新的光学系统。我们用中继式光学系统布置了两个沃尔特镜。两个光轴不在同一轴上。虽然光学系统的长度是2倍，但获得了32倍的放大倍数。由于这一改进，在实验室规模中提供了1024倍的放大。由于X射线相机的像素尺寸为24μm，分辨率优于50 nm。(2)湿样品的观察，真空室和湿样品室的窗口采用0.1SiN薄膜窗口(约500μm方形)，μm厚度。湿标本夹在两片SIN膜之间。我们将样品室放置在厚度约为2 mm的空气层中。利用发射波长在3 nm左右的连续光谱的Ta靶，成功地拍摄了鸡的湿红细胞的软X射线显微图像。(3)构建了软X射线相差显微镜，用来观察低吸收对比物。制备了两种相位板，一种是环形板，另一种是带状板。获得了直径2.8μm的乳胶球的软X射线位相衬度显微镜图像。所使用的软X射线是从铝靶发射的几个约5 nm的线谱。

Development of a soft X-ray phase contrast microscope to observe microstructure of a biological sample.(1) Construction of a high-resolution and a high-magnification optical system.We performed design and production of a high-magnification optical system to get an image of a high-resolution image in real time. In order to shorten the optical system in large magnification we propose a new optics. We arranged two Wolter mirrors by a relay optical system. Two optical axes are not on the same axis. Although the length of the optical system was 2 times, 32 times magnification was obtained. As a result of this improvement, 1,024 times magnification was provided in a laboratory scale. Because the pixel size of an X-ray CCD camera was 24μm, the resolving power of better than 50nm were provided.(2) Observation of a wet sample.SiN film windows (about 500 μ m square) of 0.1,μm thickness were used for the windows of vacuum chambers and wet sample chambers. Wet specimens were sandwiched between two pieces of SiN membranes. We set this sample chamber in the stratum of air of about 2mm thickness. Using the Ta target which emit a continuous spectrum around 3nm in wavelength, we succeeded in taking soft X-ray microscopic images of wet red blood cells of chicken..(3) Construction of a soft X-ray phase contrast microscope.We built a soft X-ray phase contrast microscope to observe a low absorption contrast object. Two kinds of phase plates were prepared, one is a ring plate and the other is a ribbon one. We obtained soft X-ray phase contrast microscopic images of latex spheres(2.8 μ m in diameter). Soft X-rays used were several line spectra around 5nm emitted from Al target.