高精度面形检测系统是同步辐射光源、大型天文望远镜等领域X射线反射镜面的重要检测仪器。为了满足第三代光源及自由电子激光对X射线反射镜面的检测需求,由光学元件加工缺陷引入的系统误差必须得到减小或消除。基于法线追迹原理设计了新型的角度检测系统,在该系统中,小孔及光源组成光束选择装置用于自动选择一束沿待测镜面测量点处法线方向传播的光束。通过测量该光束角度的变化完成对待测镜面面形的检测。将系统中光学元件紧贴小孔放置,减小或消除由相应光学元件加工缺陷引入的角度测量误差。采用法线追迹原理在大角度范围内实现高精度角度检测。
Background: High accuracy profile metrology systems are important instruments for the metrology of X-ray mirrors used in many areas like synchrotron facilities and telescopes. Many systematic errors introduced by manufacture defects of optical elements of these metrology systems will affect its performance. Purpose: This study aims to design a novel high-accuracy deflectometric profiler system to meet the state-of-art high-accuracy metrology requirement of 3rd generation X-ray light sources and X-ray free electron lasers. Methods: A new type of deflectometric profiler system, based on normal tracing principle, was proposed in which a pinhole and a light source are used to make a beam select system to automatically select a beam which propagates along the normal direction of the measured area on the surface under test. The profile information of the surface under test could be measured by measuring the angle variation of the selected beam. Results: Systematic errors introduced by manufacture defects of optical elements could be minimized by placing these optical elements as close as possible to the pinhole. Conclusion: By using the normal tracing principle method, high accuracy metrology for strong curved mirror is possible.