Development of Projection X-Ray Microscopy by Employing Pulsed Field Emission Gun

为了提高投影X射线显微镜的性能，开发高强度X射线源，寻找合适的靶材，开展了以下工作。配备场发射枪的投影X射线显微镜的研制设计并制造了配备脉冲场发射枪和静电聚焦透镜的X射线显微镜柱的所有部件。还研制了专用高压电源。目前正处于搭建和疏散测试阶段。生物样品观察的适宜靶材通过对生物样品靶材的系统研究，发现Ge、Ta、Au在较低的加速电压(10KV)下，比钛更适合于生物样品的观察。研究还发现，空气对来自这些靶的伊马京X射线的吸收也不容忽视。使用无吸收的真空摄像机，X射线图像质量显著提高，分辨率优于0.1um。场发射枪扫描电子显微镜的初步试验通过对样品台、电路等方面的改进，将场发射枪扫描电子显微镜改造为投影X射线显微镜，获得了一些硅藻土和微格子的X射线图像，具有很好的图像对比度。

In order to improve the capability of projection X-ray microscopy by developing intense X-ray source and by finding suitable target material, following subjects were carried out.1. Manufacture of projection X-ray microscope equipped with field emission gun All parts of X-ray microscope column equipped with a pulsed field emisson gun and electro-static focusing lens was designed and manufactured. A special high voltage electric power supply was also prepared. It is now in the stage of seting up and evacuation test.2. Suitable target materials for observation of biological samples From a systematic study of target materials for biological sample, it was found that Ge, Ta, Au are more suitable than Ti which has been found to be suitable for may kind of specimen, when used with rather low accelerating voltage of 10KV. It was also found that absorption of the imajing X-rays from these targets by the air is no more negligible. X-ray image quality is remarkably improved by using a vacuum camera without the absorption, showing a resolution better than 0.1um.3. Preliminary test of X-ray microscope with a field emission gun A scanning election microscope with a field emission gun was converted to a projection X-ray microscope by modifying its specimen stage, electric circuit and others, and some X-ray images of diatomite and microgrids were obtained with very good image contrast.