动态MTF的数值计算与分析

Numerical calculation and analysis of dynamic MTF

受振动的影响,在积分时间内,光学系统成像是一个动态过程。对于动态成像,常采用动态调制传递函数(MTF)作为评价振动对像质影响的工具。针对动态MTF,提出一种适用于任意运动形式的数值计算方法,该方法还可以扩展到计算二维运动时的动态MTF。该方法可用于预估和评价动态成像系统的成像质量,计算的结果还可用于运动模糊图像的仿真与恢复。鉴于在低频振动情况下,光学成像系统具有随机的动态MTF,给出平均MTF的数值计算公式,据此分析了不同情况下的成像质量。以奈奎斯特频率处动态MTF不小于0.95为约束条件,给出了可允许的振幅容限,为视轴稳定机构的参数确定提供了依据。

Influenced by vibration, the imaging of optical system is a dynamic process during the integration time. As to dynamic imaging, the dynamic modulation transfer function （MTF） is usually used as a tool to evaluate image quality. A numerical method is put forward to calculate the dynamic MTF and it is applicable in principle to any type of vibration and can be expanded to two-dimensional motion. This method can be applied for predicting and evaluating image quality of dynamic imaging systems and the results can also be used to simulate and restore motion blurred images. Due to the random MTFs with regard to situation of low frequency vibration, a numerical expression of average MTF is given. Based on it, image quality under different conditions is analyzed. Given the restriction that dynamic MTF at Nyquist frequency is no less than 0. 95, the tolerances of vibration amplitude are calculated, which can provide references for determining parameters of LOS stabilization devices.