延迟线位置偏差对太赫兹时域光谱系统的测量不确定度影响分析

Analysis of Measurement Uncertainty in THz-TDS Carried by Delay-Line Position Deviation

太赫兹时域光谱技术可以快速准确地提取材料在太赫兹波段的光学常数。然而,其各组成部分在控制精度、响应误差、系统噪音以及实验操作、数据处理等方面的误差,将影响系统对材料光学常数提取的准确性。基于透射式太赫兹时域光谱系统的测量原理,分析了系统延迟线位置偏差对提取材料复折射率准确度的影响,建立了误差在样品测量过程中的传递模型,并利用MATLAB仿真了误差对提取样品复折射率影响。结果表明,样品折射率和消光系数的不确定度受到了系统延迟线位置偏差的影响,且系统延迟线位置偏差越大,样品的复折射率提取的不确定度也就越大。同时,相比消光系数,延迟线位置的偏差对样品折射率的不确定度具有更大的影响。该模型具有一定的实际意义和理论参考价值,可分析系统延迟线位置偏差对太赫兹时域光谱系统提取材料光学常数不确定度的影响,为优化太赫兹时域光谱系统提供理论指导。

Terahertz time-domain spectroscopy can extract the optical constants of materials in the terahertz region rapidly and accurately.However,the errors of various components in the control precision,response error,system noise,experiment operation and data processing will affect the accuracy of the extracted optical constants of materials.Based on the measurement principle of transmission terahertz time domain spectroscopy,the influence on the accuracy of the system delay-line position deviation on extracting the complex index of refraction of materials was analysed in this paper,and the error on propagation through the measurement process was modeled.Simulation was carried out to illustrate the relation between the error and the uncertainty in the extracted complex index of refraction of materials.The results showed that the uncertainty of complex index of refraction of the sample is influenced by the system delay-line position.The larger the system delay-line position deviation is,the greater the uncertainty of the extraction in the complex index of refraction of the sample will be.Meanwhile,compared to coefficient of light extinction,the system delay-line position deviation has greater influence on the uncertainty of refractive index of the sample.The model has some practical significance and theoretical reference value,which can analyze the influence of the system delay-line position deviation on extracting the optical constants of materials,and provide theoretical suggestions for the optimization of terahertz time-domain spectroscopy.