Measurement of radius of curvature of spherical optical surfaces with small curvature and aperture by optical profiler
Measurement of radius of curvature of spherical optical surfaces with small curvature and aperture by optical profiler
复制标题
DOI：
10.1117/12.2073540
复制
发表时间：
2014-11
期刊：
影响因子：
--
通讯作者：
Shuang Ma;S. Yi;Shenghao Chen;Zhanshan Wang
中科院分区：
文献类型：
--
作者：
Shuang Ma;S. Yi;Shenghao Chen;Zhanshan Wang
单色能量多层Kirkpatrick-Baez显微镜是惯性约束聚变研究的重要诊断工具之一。它由两个曲率和孔径较小的正交凹面球面镜组成，通过在每个垂直方向上独立采集X射线来产生物体的图像。凹面球面镜曲率半径的准确测量是实现其成像质量、光学吞吐量和能量分辨率等光学性能设计的关键。然而，对于小曲率、小口径的球面光学面曲率半径难以用常规方法测量，因为产生的玻璃反射强度太低，不能正确测量。本文提出了一种改进的光学轮廓仪测量方法，以实现单色能量多层Kirkpatrick-Baez显微镜所用小曲率小孔球面光学面曲率半径的精确测量。首先，在每次实验前，我们使用一个标准的超光滑光学平台来标定参照镜。然后利用牛顿环理论对测量区域中心位置与干涉图中心位置的偏差进行修正，并根据干涉原理推导出零级条纹位置，即在光程差为零时，表面粗糙度最小。光学轮廓仪的测量结果表明，相对误差小，重复性好。最后，通过单色能量多层Kirkpatrick-Baez显微镜的成像实验，确定了曲率半径的测量精度。
Monochromatic energy multilayer Kirkpatrick-Baez microscope is one of key diagnostic tools for researches on inertial confinement fusion. It is composed by two orthogonal concave spherical mirrors with small curvature and aperture, and produce the image of an object by collecting X-rays in each orthogonal direction, independently. Accurate measurement of radius of curvature of concave spherical mirrors is very important to achieve its design optical properties including imaging quality, optical throughput and energy resolution. However, it is difficult to measure the radius of curvature of spherical optical surfaces with small curvature and aperture by conventional methods, for the produced reflective intensity of glass is too low to correctly test. In this paper, we propose an improved measuring method of optical profiler to accomplish accurate measurement of radius of curvature of spherical optical surfaces with small curvature and aperture used in the monochromatic energy multilayer Kirkpatrick-Baez microscope. Firstly, we use a standard super-smooth optical flat to calibrate reference mirror before each experiment. Following, deviation of central position between measurement area and interference pattern is corrected by the theory of Newton’s rings, and the zero-order fringe position is derived from the principle of interference in which surface roughness has minimum values in the position of zero light path difference. Measured results by optical profiler show the low relative errors and high repeatability. Eventually, an imaging experiment of monochromatic energy multilayer Kirkpatrick-Baez microscope determines the measurement accuracy of radius of curvature.