地球同步轨道(GEO)空间没有大气干扰,光束在GEO空间中传输不会衰减,也不会出现波面畸变,是合成孔径激光雷达(SAL)技术的理想应用场所。天基SAL可为GEO目标提供超衍射极限分辨率的光学图像。为了实现这一目标,利用在万有引力作用下绕地心沿不同圆周轨道运动的天基SAL和GEO目标的三维坐标关系,建立了基于光学外差探测的天基SAL成像理论模型,研究了与轨道参数有关的成像数据处理方法。研究结果表明,利用万有引力轨道运动,天基SAL能够对GEO目标实现超衍射极限分辨率成像;轨道半径、轨道平面夹角、成像位置等参数的变化会影响成像数据的处理过程,降低成像分辨率,造成聚焦图像的几何形变。交会点附近是天基SAL最佳的成像位置,此处天基SAL与GEO目标之间的距离近,聚焦图像的几何形变小,成像分辨率高。

Geosynchronous orbit (GEO) space is an ideal place for the synthetic aperture ladar (SAL) technology because there is no atmospheric interference and no attenuation and wavefront distortion during beam transmission in it. A space-borne SAL can provide the optical image of a GEO target with ultra-diffraction-limited resolution. To realize this aim, we establish the theoretical model of space-borne SAL imaging based on optical heterodyne detection and investigate the imaging data processing methods related to the orbital parameters, using the three-dimensional coordinate relationship between the space-borne SAL and the GEO target moving along different circular orbits around the earth's core under the effect of universal gravitation. The research results show that the space-borne SAL can produce super-diffraction-limit imaging of a GEO target using the gravitational orbital motion. Besides, the changes of orbit radius, orbital plane angle and imaging position show certain influence on the processing of imagining data, reduce imaging resolution and result in the geometric deformation of the focused image. Moreover, the position near the intersection points is the best position for space-borne SAL imaging, where the distance between the space-borne SAL and the GEO target is small, and thus the geometric deformation of focused images is small and the imaging resolution is high.