一种机载合成孔径成像激光雷达聚束模式成像算法

Algorithm for Airborne Spotlight Synthetic Aperture Imaging Ladar Data Processing

合成孔径成像激光雷达是一种新的主动式有源的成像系统,可以获得比合成孔径雷达更高的分辨率,和更接近光学图片的效果。首先,在理想条件下分析了调频连续波的信号模型,推导出在连续波系统聚束模式下一种适用于机载合成孔径成像激光雷达系统的频率变标算法。然后,使用傅里叶变换法对符合von Karman谱的随机相位屏模拟大气湍流,并分析了Fried参量和合成孔径长度之间的关系。最后,仿真说明真空中采用方位预处理可以消除图像重影,并且补偿多普勒频移项可以消除8.6～9.3dB的能量损失和使图像散焦的现象。而在有大气影响时,合成孔径长度的选择小于Fried参量时,图像方位向可以良好聚焦。

Synthetic aperture imaging ladar is new active imaging system,which can offer a finer azimuth resolution than that achievable in conventional synthetic aperture radar（SAR）system.The frequency-modulated-continuous-wave（FMCW）signal is analyzed,and the frequency scaling algorithm,which is suitable for airborne synthetic aperture imaging lidar（SAIL）system using FMCW signal in spotlight model,is deduced.And then,simulation of phase screen（PS）distorted by atmospheric turbulence following the von Karman spectrum by using Fourier transform is implemented in order to simulate turbulence.Finally,simulation shows that in the vacuum azimuth preprocessing can remove the ambiguity of the image and the modified algorithm can eliminate the loss of peak power about 8.6～9.3 dB and the defocusing phenomenon,while considering the effect of the atmospheric turbulence,if the synthetic aperture length does not exceed the similar Fried parameter of the atmosphere for SAIL,a well focused image can be obtained.