高分辨率成像光纤传像束制备工艺的进步使得传统高性能光电成像仪器具备柔性, 并且使仪器的体积和重量大幅减小。面阵光纤传像束和面阵CCD间的像元耦合离散采样效应, 导致了传统成像质量评价模型的局限性。从光强度呈余弦分布的光信号在面阵光纤传像束和面阵CCD中的传递过程出发, 建立了耦合离散采样系统的耦合调制传递函数(Coupled-MTF)模型, 研究了Coupled-MTF的收敛特性及其随像元耦合误差的变化规律等。研究表明, 若输入信号的空间频率与奈奎斯特频率的偏差为1%, 当阵列中包含的像元总数超过1000时, Coupled-MTF振荡收敛为固定值。输入信号的空间频率与奈奎斯特频率的偏差越小, Coupled-MTF振荡收敛的速度越慢。Coupled-MTF的振荡幅值在弧失和子午方向不同, 且与各自方向的像元耦合误差有关。Coupled-MTF随面阵光纤传像束与面阵CCD间的像元耦合误差周期振荡, 理论上振荡周期为包层直径。在奈奎斯特频率及其分频附近的频域, Coupled-MTF在给定空间频率处不为固定值。上述特性有别于传统空不变成像系统的调制传递函数。

For the advancements of imaging fiber bundle fabrication technology with high resolution, traditional high-performance photoelectric imaging instruments become flexible with greatly reduced volume and weight. However, traditional image quality evaluation models are limited by the pixel coupling discrete sampling effect of array fiber image bundles and array CCD. On the basis of the transfer process of grayscale cosine distribution optical signal in array fiber image bundles and array CCD, a mathematical model of coupled modulation transfer function (Coupled-MTF) for coupled discrete sampling system is established. Results show that the coupled-MTF converges to a fixed value when the deviation between an input signal spatial frequency and Nyquist frequency is 1% and the total number of pixels in the array is more than 1000. A small frequency deviation corresponds to a slow convergence velocity of the coupled-MTF oscillation. The oscillation amplitude of coupled-MTF differs in tangential and sagittal directions in a manner related to the corresponding pixel coupling deviation. The coupled-MTF periodically oscillates with the coupling deviation between the array fiber image bundles and the array CCD. One cycle is equivalent to the diameter of fiber cladding. The results show that the coupled-MTF shows different characteristics from the modulation transfer function of classical space invariant imaging system.