机载合成孔径激光雷达相位误差补偿研究

Phase Error Compensation in Airborne Synthetic Aperture Lidar Data Processing

为了研究大气湍流对合成孔径激光雷达(SAL)成像的影响,基于Monte-Carlo随机因子,对满足Kolmogorov统计规律的大气湍流相位屏进行数值模拟,计算了不同湍流、不同波长情况下的机载SAL成像结果,数值分析了不同斜距、不同波长条件下合成孔径长度与大气相干长度比值随大气湍流强度的变化关系。结果表明大气湍流效应严重影响了SAL的方位向成像,随着湍流强度的增大,SAL图像散焦越来越严重,直至目标无法分辨。同一湍流强度下,光束波长越长,SAL成像效果越好。对于湍流效应造成的SAL图像失真,采用改进的秩一相位误差估计(IROPE)法对SAL图像进行补偿,当大气相干长度大于实孔径长度时,IROPE算法能够有效改善图像的聚焦效果,提升SAL成像分辨率。

In order to study the influence of atmospheric turbulence on the image of synthetic aperture lidar （SAL）, based on Monte-Carlo random factor,numerical simulation of phase screens following the Kolmogorov spectrum is introduced. The SAL images with different turbulence and different wavelengths are calculated. Additionally, with different wavelengths and slant ranges, the relations of turbulence intensity and the ratio of synthetic aperture length to atmospheric coherent length are analyzed. The results show that the atmospheric turbulence can severely affect the azimuth resolution of the SAL image. With the increase of turbulence intensity, SAL imaging defocus is becoming more and more serious, and eventually the target can not be distinguished. With the same turbulence intensity, when the beam wavelength is longer, the SAL image quality is better.For the distortion of SAL image caused by turbulence effect, improved rank one phase error estimation （IROPE） method is used to compensate the phase errors. When the atmospheric coherent length is greater than the real aperture length, IROPE method can effectively improve the focusing effect of images and increase the imaging resolution.