航空摆扫成像像移计算与误差分配

Image motion calculation and error distribution for aerial whisk-broom imaging

航空摆扫成像时,曝光时间内像点的移动是影响成像质量的重要因素。为了研究三面镜各项误差对像移量的影响,利用齐次坐标变换法建立了像点位移计算模型,准确地引入了摆扫镜轴系误差等常见误差项。在此基础上,分析了三面镜加工装调误差对像点位移量的影响,并比较了像点位移量对各误差项变化的灵敏度。接着,根据系统调制传递函数的指标对像点位移量的范围进行了限定,确定了高图像质量允许的像点位移量。最后,对分配后的三面镜误差进行了蒙特卡罗法仿真。仿真结果表明,像点位移量在10^-5 m量级,像移的MTF因子为0.97,满足指标要求。该结论对摆扫相机的结构设计与加工装调有重要的参考价值。

Image motion in the exposure time is a critical factor that affects image quality in aerial whisk-broom imaging.To study the influence of error factors in swing imaging of a three-mirror reflector on image displacement,a calculation model of image motion was first established using homogeneous coordinate transformation.Common error terms such as the precision of the rotation axis of the sweeping mirror were then introduced to the model.On this basis,the effects of machining and assembling errors of the three-mirror reflector on the displacement of the image points were analyzed,and the sensitivities of errors to image motion were compared.Then,based on the Modulation Transfer Function(MTF)of the system,the error limits of image point displacement were set,and the allowable displacement of the image point with high image quality was determined.Finally,the error distribution of the three-mirror reflector was simulated using the Monte Carlo method.The simulation results show that the image displacement is 10-5 m magnitude and the MTF is 0.97,which meet the requirements of the target.These findings have significant reference value for the structural design and machining adjustment of swing cameras.