基于热弯玻璃的圆锥近似Wolter-I型X射线聚焦望远镜采用在凸柱面镜模具上热弯超薄玻璃的反射镜片制作方式, 柱面镜低频面形误差和中频波纹度是影响望远镜聚焦性能的主要因素, 因此高精度快速检测凹凸柱面镜中低频表面误差是研制中的关键技术。传统的柱面样板法无法检测超薄镜片, 且只能检测对应样板半径的面形, 检测效率低, 无法满足要求。采用基于计算全息的零位补偿干涉检测法和激光扫描两种方法, 对超光滑凸柱面模具和超薄凹柱面镜片进行快速定量检测, 计算了两种检测方法的功率谱密度, 通过表面的斜率误差拟合得到点扩散函数曲线和半功率直径。结果表明: 两种方法都能够快速定量表征中低频表面误差对X射线望远镜角分辨率的影响, 为提高反射镜制作精度和改善X射线望远镜聚焦性能提供了技术支撑。

The manufacturing technology of cylindrical mirror used in conic approximate Wolter-I X-ray focusing telescope is hot slumping glass segments, which makes the thin glass substrate replicated on the convex surface of cylindrical mandrel. The most important errors of cylindrical glass are the figure error and ripple error, which are the major factors affecting the focusing performance of telescope. Therefore, the high-precision and quickly measuring low and mid spatial frequency error of concave surface and convex surface of cylindrical glass is the key technology in manufacturing process. The traditional test plate can′t meet the requirements because it can only measure specific surface with the same of radius of the test plate inefficiently and can′t measure the thin glass. The convex surface of smooth cylindrical mandrel and concave surface of thin cylindrical glass were measured by an interferometer with both computer generated hologram (CGH) and laser scanner quickly and quantitatively. Also, with the two testing methods, the power spectral density(PSD) of cylindrical glass was calculated and the point spread function (PSF)and half power diameter (HPD) were plotted by fitting slope error. It demonstrates that the two methods can characterize the influence of the low and mid spatial frequency error on the angular resolution of X-ray telescope, which benefit for improving the precision of the manufacturing mirror and the focusing performance of X-ray telescope.