合成孔径激光成像雷达(Ⅰ):离焦和相位偏置望远镜接收天线

把合成孔径激光成像雷达的目标衍射区分为三个区域,提出采用离焦或者附加空间相位调制板的光学接收望远镜补偿回波像差。当目标处于菲涅耳衍射区时可采用离焦或偏置望远镜补偿回波二次项离焦像差并产生用于孔径合成的二次项相位历程;目标处于夫琅和费衍射区时可以采用离焦或偏置望远镜补偿回波二次项离焦像差但不产生相位历程;目标处于瑞利-索末菲衍射区域时不可能补偿回波高阶像差。

The diffraction from a target for a synthetic-aperture laser imaging radar is distinguished into three domains, and the methods of defocusing of telescope and spatial phase modulation by an additional plate are suggested to compensate the wavefront aberration of echo. In the Fresnel diffraction region the quadratic aberration of echo can be eliminated by the defocused or phase-biased telescope and a phase history for aperture synthesis is correspondingly generated, and in the Fraunhofer region the quadratic wavefront can be also eliminated by the defocusing or phase-biasing but no phase history. Nevertheless, in the Rayleigh-Sommerfeld diffraction the higher-order aberrations cannot be compensated.