红外光电成像系统MTF测试技术分析

调制传递函数是评价红外光电成像系统整机成像质量的重要指标之一。通常MTF的测试方法有狭缝法和刀口法等。详述了倾斜目标靶（斜狭缝和斜刀口）测试MTF的测试原理，并且对该两种方法进行了比对实验。提出一种改进刀口法，将多行数据刃边对齐并排列成一行数据作为刀口扩散函数,能增加采样点数和采样率并提高测试分辨率，进而得到刀口图像，对每行数据先微分得到各行LSF(线扩散函数)，再对LSF多行数据构成的新图像按照斜缝法处理过程计算MTF。实验验证表明，该方法数据能够有效地降低在MTF测试过程中的噪声影响，与斜缝法MTF测试结果差值最大不超过7.5%。

MTF test technology analysis of infrared electro-optical imaging system

Modulation transfer function (MTF) is one of the important indexes to evaluate the image quality of infrared electro-optical imaging system. The testing principle of MTF test by tilting target (slit or knife-edge) was detailedly analyzed, and the contrast test about the two methods was carried out. An improved knife-edge method was proposed, multiple rows of data knife-edge were aligned and arranged in a row of data as a edge spread function, which could significantly increase the simpling points, improve simpling rate and testing resolution, and the knife-edge image was obtained. Line spread function (LSF) of each row was got by differentiation, the MTF of the new image composed of LSF multiple rows of data was  calculated by canted slit method. Experimental results indicate that, the proposed method is simple and can effectively reduce the noise impact during MTF test process, the difference of the test result is not more than 7.5% compared with the canted silt method.