MTF曲面构造方法研究

Research of MTF Surface Construction Methods

调制传递函数(modulation transfer function,MTF)是定义在二维频率域空间的实函数,可用一个MTF空间曲面描述,是光学成像系统成像性能的一种重要的评价指标。由于成像系统的二维MTF曲面不能直接测量,需要先测量几个特定方向的一维MTF曲线,再由曲面构造方法间接获得。对于同样的MTF曲线组,用不同方法构造出的MTF曲面各不相同,因此有必要研究MTF曲面构造方法的有效性。文章对现有构造MTF曲面的乘积法和插值法进行分析,提出一种新的旋转插补法,并使用(准)高斯函数和4次多项式函数作为二维MTF曲面的模拟标准,对上述3种方法的有效性和误差分布进行定量分析。实验结果显示,旋转插补法具有更好的适用性。

Modulation transfer function （MTF） is a real function defined by the 2-D spatial frequency domain and could be described by a space MTF surface. Although the 2-D Modulation Transfer Function （MTF） surface of imaging system could not be measured directly, it could be constructed by measuring 1-D MTF curves in several specific directions. The 2-D MTF surfaces thus created are not the same, however, this method of construct 2-D MTF surface deserves to ensure its effectiveness. We analyze the current methods of MTF surface construction, product method and interpolation method, and then propose a novel rotation interpolation method. The （quasi） Gaussian function and the 4-degree polynomial function are designed and used as the MTF surface hypothetic standards. By comparing the effectiveness and error distributions between the various methods, the rotation interpolation method is better in applications.