本文针对差分合成孔径激光雷达(DSAL)未来应用场景具有回波信号微弱、平台与目标之间存在运动误差的特点，在微弱回波条件下进行了随机活塞运动目标的DSAL成像演示实验。采用波长为1 550 nm的激光源，搭建了DSAL成像系统，接收孔径间距为188 μm，目标距离为2.4 m。通过在发射端加入偏振片对发射功率进行衰减，并利用步进线性平移台给目标到雷达之间的光程引入随机活塞运动误差。在激光发射功率约为50 nW和20 nW的情况下，对光程变化在［-5 μm, 5 μm］的随机活塞运动目标进行DSAL成像实验，此时合成孔径激光雷达(SAL)图像由于随机相位误差而完全散焦，DSAL图像则聚焦良好。实验结果表明，在微弱回波条件下，DSAL系统仍能较好地消除相位误差，实现稳定成像。

Weak echo signal and motion errors are the features of differential synthetic aperture ladar (DSAL) that should be addressed in its future application scenarios. To achieve this, a laboratory DSAL demonstration of random piston motion target at very low return level is reported. Using 1 550 nm laser source, a DSAL imaging setup is built, with receiving apertures spacing of 188 μm and target distance of 2.4 m. The transmitted laser power is attenuated by adding a polarizer to the transmitter and random piston motion errors are introduced into the optical path between the target and the ladar, by using a stepping linear translation platform. At the transmitted power of approximately 20 nW and 50 nW, DSAL imaging experiments are carried out for random piston motion target with optical path variation range of -［5 μm, 5 μm］. Under these experimental conditions, the synthetic aperture ladar (SAL) images are completely defocused due to random phase errors, but the DSAL images are well focused. The results indicate that the DSAL system could eliminate phase errors and achieve stable imaging at very low return levels.