为了能对红外热成像系统的性能进行准确的评价，必须对其MTF进行准确测试。利用高精度双黑体反射靶标评估系统，并依据刀口靶测试原理，首先在计算机中进行微分运算，获得线扩展函数，然后再进行傅里叶变换，最终获得MTF。通过对CEDITⅡA型热像仪MTF的测试和分析，发现MTF的测试主要受输入差分信号强度，脉冲电平的去除与否，以及采集到的信号是否滤波等因素的影响。该测试评估系统能保证背景辐射的均匀性和稳定性，且受环境温度变化的影响极小，因此可大大提高测量的准确性和可靠性。

In order to accurately evaluate the performance of an infrared thermal imager,it is necessary to test its modulation transfer function (MTF). In this paper,a CEDIT Ⅱ A thermal imaging system is measured and analyzed by the equipment with dual blackbody and reflective target system. The new testing method utilizes the theory of edge target test. The edge is differentiated to obtain the line spread function and Fourier-transformed to get the MTF. It is discovered that the primary factors which affect MTF test are the signal intensity for the testing system incidence,impulse noise suppression and acquisition filtering,etc. The equipment can keep even and steady radiation,and is not affected by ambient temperature,so the accuracy and reliability of measurement can be improved.