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1.性能参数及其测量 (1)噪声等效温差(或反射率差)NEΔT(NEΔρ):这是衡量系统判别噪声中小信号能力的惯用参数,测量该参数的主要问题是目标和背景温度的测量和比辐射率δ的影响。我们采取了控制目标和背景的温差、对背景的环境作一般的局部保温措施、温差精度的校正等方法解决了这个问题。 (2)调制传递函数MTF:系统的点(或线)扩展函数的傅里叶变换的模称为调制传递函数,MTF的测量方法一般是输入一个δ函数即空间频谱很宽的针孔或狭缝目标,然后在系统输出处测出其响应函数点(或线)扩散函数,作规一化处理后进行傅里叶变换计算得到MTF。由MTF可求得系统分辨率、上升距离和系统截止频率。
1. Performance parameters and their measurements (1) Equivalent noise temperature difference (or reflectance difference) NEΔT (NEΔρ): This is a conventional parameter used to measure the system’s ability to discriminate noise from small signals. The main problems in measuring this parameter are the target and background temperature The effect of measurement and emissivity δ. We have taken control of the temperature difference between the target and background, the background of the environment for general local insulation measures, such as temperature accuracy correction method to solve this problem. (2) Modulation Transfer Function MTF: The point (or line) of the system is called the modulation transfer function of the Fourier transform of the extended function. The measurement method of MTF is usually to input a delta function, that is, a pinhole with a wide spatial frequency spectrum or a narrow The target is then measured at the output of the system to determine the point (or line) diffusion function of the response function. The normalized Fourier transform is used to calculate the MTF. The system resolution, rising distance and system cut-off frequency can be found by MTF.