刀口法是测量X射线探测器调制传递函数(MTF)的主要方法之一,但影响测量精度的因素很多,正确的数据处理是提高测量精度的关键。提出了一种组合数据处理方法,系统地降低了测量带来的误差,从而实现了高分辨X射线CCD调制传递函数的测量。实验前仿真调制传递函数,预测曲线走势和噪声干扰。利用自适应平均行数算法、回型窗法和哈夫变换得到刀口倾斜角来纠正MTF曲线。提出了局部曲线分析法,以定量分析曲线波动情况,消除前人视觉判断的主观误差。通过上述算法得到的MTF曲线的均方差仅为0.011,Nyquist频率误差为2.52%。

Knife-edge method is one of the main methods to obtain the modulation transfer function (MTF) of X-ray detectors,while data processing is critical to the accuracy. A series of data processing methods is presented,which can improve the measurement accuracy of MTF for a high-resolution X-ray CCD. Before experiments,MTF simulation is employed to predict the curve trend and noise level. Subsection-analysis algorithm is used to analyze the curve fluctuation in order to eliminate the subjective errors. MTF is recorrected by the oblique angle of the knife edge,which is gotten by using self-adaptive algorithm,clip-window algorithm,and Hough transform. After all the procedures,the mean square deviation of 0.011 for the MTF is achieved,while the Nyquist frequency error is 2.52%.