国家同步辐射实验室反射率计误差分析

Error Analysis for Reflectometer in National Synchrotron Radiation Laboratory

中国科技大学国家同步辐射实验室"光谱辐射标准与计量实验站"上的反射率计主要用于测量各种光学元器件在X射线、真空紫外波段的反射率。为保证测试结果的精确性和可靠性,在大量实验数据的基础上,结合必要的理论推导,对反射率计测试误差来源及影响程度进行了分析,确定影响反射率计测试精度的主要因素包括光源、探测器、样品安装等。总结了光源波动、探测器损坏的几种典型形式,定性、定量地分析了这些因素和样品安装、光斑尺寸对测试精度的影响,针对性地提出了应对办法,把测试误差控制在2%以内,从而有效地保证了测试精度。

The reflectometer in spectral radiation standard and metrology beamline of Hefei National Synchrotron Radiation Laboratory mainly measures reflectance and transmittance of vavious reflecting coatings in X-ray and vacuum ultraviolet wavelength region. To ensure the accuracy and reliability of the measurement, the error sources of the reflectometer and their influence on measurement were investigated. Based on experimental data and theoretic calculation, it has been found that the accuracy of the measurement is significantly dependent on the stability of the synchrotron radiation, the detector and the fixing of the sample. Several typical forms of the radiation fluctuating, detector damage and sample fixing are summarized, and their influences as well as influence of light spot size on measurement are analysed quantitatively and qualitatively. Some effective measures are taken to control the measurement error within 2 %.