玻璃基底Wolter-1型X射线聚焦镜研制及测试

Wolter-1型X射线聚焦镜可将掠入射的X射线反射至焦平面处，具有较强的成像探测能力，在天文探测等领域中具有重要作用.通过建立几何模型对反射镜面及反射光线方程进行理论计算，推导出了适用于以玻璃为基底材料的聚焦镜设计参数方程，可用于对此类聚焦镜进行理论设计，依据理论设计，采用具有极高表面光洁度的超薄肖特D263T玻璃经热弯成型后作为反射镜基底，在反射镜表面制备金属铱薄膜作为反射膜研制了Wolter-1型反射镜组，并使用激光三维扫描仪对所研制的聚焦镜片面型进行了测试.测试结果显示，实际镜片面型与理想镜片面型公差在10 μm以内的测试点占总测试点的50%.通过搭建可见光条件下的焦斑测试系统，使用图像采集相机采集焦斑的灰度图像，通过图像分析软件分析计算该灰度图像的灰度分布来定量分析焦斑的能量分布情况，从而确定焦斑特性参数.实验结果显示：研制出的聚焦镜片焦距为1.6 m，焦斑的半能量包围直径为0.33 mm，对应角分辨率为0.7角分.

Development and testing of glass substrate Wolter-1 X-ray focusing mirror

The wolter-1 X-ray focusing mirror can reflect grazing incidence X-ray to the focal plane, which plays an important role in the astronomical detection and other fields due to its good image detecting capability. A geometric model of the optical system is established for theoretically deriving the optical path equations which is useful in this glass based focusing mirror designing, all the design parameters of the focusing mirror can be obtained by solving these equations. In the manufacturing process, the D263T glass is chosen to be the structural material of the focusing mirror due to its light weight and super smooth surface, after a slumping process, the flat glass mirror will have the shape of Wolter-1 X-ray focusing mirror. This slumping process has been used successfully in the manufacturing process of an American mission named The Nuclear Spectroscopic Telescope Array, which was launched in 2012. According to X-ray reflecting theory, the reflectivity of the Wolter-1 mirror can be improved significantly by coating metal film on the surface of the mirror. In this work, an iridium film is coated on the surface of the glass mirror through a vacuum evaporating process. In order to learn the influence of the focal spot caused by the mirror shape tolerance, the morphology of the mirror is tested by using a 3-D laser scan instrument. The results show that 50% of the total test points are located in the tolerance range of-10-10 μm, in which the tolerance represents the difference between the actual lens profile and the ideal lens profile. Then the focal spot test is carried out with the help of a visible light test system:a laser collimator is installed in front of focusing mirror as an incidence light source, and a charge coupled device (CCD) is placed in the focal plane to gather the image of the focal spot, by calculating the gray level distribution of the focal spot image taken by the CCD, the energy distribution characteristic of focal spot can be obtained. The experimental results show that the focal length of the focusing mirror is 1.6 m, and the half-power surrounding diameter of the focal spot is 0.33 mm, corresponding to the angular resolution of 0.7 arc min.