大气湍流下合成孔径激光雷达成像数值模拟及PGA补偿

Numerical Simulation on Synthetic Aperture Ladar Imaging Through Atmospheric Turbulence with Phase Gradient Algorithm Compensation

为研究大气湍流对合成孔径激光雷达(SAL)的成像影响,采用谱反演法对符合Kolmogorov谱的大气随机相位屏进行了数值模拟,给出了单层及多层叠加的随机相位屏图像;然后以多层随机相位屏叠加方式模拟实际大气湍流,计算了无湍流、弱湍流、中等湍流和强湍流等情况下理想机载单站聚束式SAL对点目标以及扩展目标的成像,模拟成像表明大气湍流对SAL成像的方位分辨率有严重影响,湍流越强,图像方位向分辨率越差;针对湍流造成的SAL图像方位向分辨率降低,采用相位梯度自聚焦(PGA)算法对SAL图像进行了方位向补偿,结果有效地改善了图像的聚焦效果,提高了成像质量。

To investigate the influence of atmospheric turbulence on the image of synthetic aperture ladar（SAL）, numerical simulation of phase screens following the Kolmogorov spectrum by using spectrum inverse transform is introduced and detailed pictures of monolayer or multilayer random phase screens are given,then the calculated multilayer random phase screens are used to simulate the real atmospheric turbulence.In an ideal monostatic airborne spotlight SAL imaging system,detailed calculations on the SAL images with point or extended targets through no, weak,medium and strong turbulence are illustrated.The results vividly show that the atmospheric turbulence can severely affecte the azimuth resolution of the SAL image and with the increase of the atmospheric turbulence,the distortion of the SAL image deteriorates.To correct the degraded SAL images induced by atmospheric turbulence, phase gradient algorithm（PGA） method is implemented in azimuth,and the effort shows a significant improvement in the guality of the SAL image.