光学学报, 2015, 35 (7): 0711001, 网络出版: 2015-06-26
正弦振动下动态调制传递函数分析与研究
Dynamic Modulation Transfer Function Analysis and Research under Sinusoidal Vibration
成像系统 调制传递函数 正弦振动 像质评价 imaging systems modulation transfer function sinusoidal vibration image quality assessment
摘要
振动导致航空相机成像分辨率下降,常采用动态调制传递函数(MTF)评价振动对成像质量的影响。根据线性光学系统的传递函数理论,针对任意频率的正弦振动,提出一种基于第一类贝塞尔函数的动态MTF 计算方法,并以奈奎斯特频率处动态MTF 不小于0.9为条件,得出低频振动的振幅容限随频率增加而减小,高频振动的振幅容限为0.2 pixel。通过对刀口靶标进行正弦振动下动态成像实验,得出理论计算结果与实验结果间相对误差小于4.25%,相比以往相关文献的分析结果,计算精度最大可提高18.5 倍,因此该方法可用于预估和评价振动环境下航空相机的成像质量,对视轴稳定系统的设计具有指导意义。
Abstract
The image resolution of aerial camera declines resulting from vibration and the dynamic modulation transfer function(MTF) is used to evaluate the impact of vibration on image quality. In accordance with the transfer function theory of linear optical system, a formula based on Bessel function of the first kind is established to calculate dynamic MTF for sinusoidal vibration at any frequency. The tolerance of vibration amplitude is calculated with the restriction that dynamic MTF at Nyquist frequency is no less than 0.9. For low-frequency, the amplitude tolerance declines as frequency rises. And the tolerance of high-frequency is 0.2 pixel. The dynamic imaging experiment of the edge target under sinusoidal vibration is carried out. The experiment shows that the relative error between the MTFs calculated from the derived formula and the MTFs obtained by slanted-edge method from the practical degraded image is less than 4.25%. The accuracy rises 18.5 times compared with other relevant literature. Therefore, the proposed formula can be used to estimate and evaluate the image quality of aerial camera under vibration and is significant for the design of the line-of-sight stabilization system.
杜言鲁, 丁亚林, 许永森, 聂品. 正弦振动下动态调制传递函数分析与研究[J]. 光学学报, 2015, 35(7): 0711001. Du Yanlu, Ding Yalin, Xu Yongsen, Nie Pin. Dynamic Modulation Transfer Function Analysis and Research under Sinusoidal Vibration[J]. Acta Optica Sinica, 2015, 35(7): 0711001.