针对逆合成孔径激光雷达对机动目标成像时, 其回波信号存在距离向色散和方位向多普勒时变的问题, 在建立机动目标精确回波信号模型的基础上, 提出一种基于积分立方次相位函数-分数阶傅里叶变换的成像算法.在距离压缩时, 首先采用积分立方次相位函数快速估计出回波脉冲的调频率, 进而在最佳旋转角下采用分数阶傅里叶变换实现距离像压缩, 消除距离色散.经过运动补偿后, 在方位压缩时结合积分立方次相位函数-分数阶傅里叶变换与Clean技术实现对每一距离单元上强弱散射点的分离成像, 解决由于机动运动产生的方位多普勒时变而形成的图像散焦问题.最后, 通过散射点模型的仿真实验, 验证了所提方法的有效性.

To solve the problem of range dispersion and azimuth Doppler time-variation in echo when imaging maneuvering target with inverse synthetic aperture ladar, the accurate echo model of maneuvering target is built, and an imaging algorithm based on integral cubic phase function-fractional Fourier transform is proposed. In range compression, the integral cubic phase function is used to estimate the modulation frequency of the echo pulse quickly, and then the fractional Fourier transform is used to realize the range compression at the optimal rotation angle. In this way, the range dispersion is eliminated. After motion compensation, the integral cubic phase function-fractional Fourier transform is combined with the Clean technique to achieve the separation imaging of the strong and weak scattering points on each range cell, solving the problem of image defocusing due to the azimuth Doppler time-varying. Finally, the validity of the proposed method is verified by the simulation experiment of scatter point model.