FTIR 光谱仪动镜速度和采样抖动的噪声分析

摘要

Spectral noise induced by the random errors of mirror-velocity and sampling jitter in Fourier-transform spec-trometer is analyzed.A model based on Noise Equivalent Radiance Difference(NERD)and Noise Equivalent Tempera-ture Difference(NETD)is established.The analytical results show that the mirror-velocity associated with the ampli-tude variations and the time delay of the anti-aliasing filter and the sampling jitter can lead to system noise.Then,the noise impact of mirror-velocity and sampling jitter is simulated and calculated by MATLAB;the theoretical model is verified;the noise of the actual instrument is evaluated,which provides the basis for mirror control,anti-aliasing filter design,noise calculation and improvement of Fourier-transform spectrometer.%分析了傅里叶变换光谱仪由动镜速度和采样抖动的随机误差引起的光谱噪声，建立了基于噪声等效辐亮度差（NERD）和噪声等效温差（NETD）的噪声模型。分析表明，动镜速度的波动与抗混叠滤波器幅频响应、时间延迟的综合作用，以及采样触发的短时抖动，都会引起系统的噪声。通过 MATLAB 数值模拟，对动镜速度和采样抖动的噪声影响进行了仿真分析与模型计算，验证了理论模型，评估了实际仪器的噪声水平，为动镜控制、抗混叠滤波器的设计以及傅里叶变换光谱仪的噪声定量化计算和改善提供了依据。