傅里叶望远镜重构图像虚像分析  

Analysis on reconstruction of virtual images of Fourier telescopy

作　　者：于树海[1] 董磊[1] 刘欣悦[1] 凌剑勇 

机构地区：[1]中国科学院长春光学精密机械与物理研究所,长春130033

出　　处：《物理学报》2015年第18期283-288,共6页Acta Physica Sinica

摘　　要：研究了采用T型激光发射阵列情况下傅里叶望远镜重构图像的虚像问题,基于系统成像基本原理,明确了虚像的来源.分析认为,发射光束在x和y轴扫描时,在俯仰角误差的作用下,抽取目标的空间频率和设定值之间存在一定的偏差;当进行轴向和象限相位闭合、计算目标的单一傅里叶分量时,该偏差会对频谱的频移造成随机的相位影响,反映在空域上使得重构图像存在虚影现象.在不同扫描方式情况下,采用下一步外场实验参数,通过计算机模拟证实了上述分析的正确性.Fourier telescopy can realize high resolution imaging to remote,small and dim target by using laser as the light source.The signal-to-noise ratio of imaging system is easy to improve by increasing the area of receiver.However,numerical simulation shows that the reconstruction images sometimes has a virtual phenomenon.It reduces the quality of reconstruction images,and even cannot have a resolution to the imaging target.Based on Fourier telescopy imaging principle,using T type transmitting array,the reason of forming virtual images is indicated by mathematical deduction.The spatial frequency error between the actual getting and setting would be produced when the laser beams scan the x or y axis with pitch error.The error would cause the random phase influence when calculating the single Fourier frequency of target by using phase closure on the axis and quadrant scan.Using integrated spatial frequency of transmitter array to reconstruct the image of target would cause a virtual phenomenon.By contrasting reconstruction images it is found that the image quality is reduced seriously,even the virtual phenomenon appears when the transmitting system is axially scanned with,pitch error,and it decreases slightly on quadrant scan.In the present paper,we consider the reason of the phase closure of quadrant of T type transmitting array relies on axial frequency.At the same pitch error,different scan methods would cause different reconstruction images.The directions of virtual images are the same within the axial error.The computer simulation confirms the validity of the above analysis by three different modes of transmitter array through using the next field experiment parameters.

关 键 词：傅里叶望远镜 空间频率偏差 图像重构 

分 类 号：TH751[机械工程—仪器科学与技术] TP391.41[机械工程—精密仪器及机械]