Imaging Technology For Inverse Synthetic Aperture Lidar Based On Nelder-mead Simplex Method

The traditional imaging method in optical domain is constrained by diffraction limitation of received aperture,and is difficult to obtain high-resolution(centimeter level)image for target far away from observation station under existing conditions.Inversed synthetic aperture lidar,or ISAL for short,serves as a new image detection system,is hopeful to become an effective technology of high-resolution sensing for remote target,because of its imaging resolution having no connection with detection range theoretically.According to the application requirements for high-resolution detection of remote target,the thesis conducts research project related to ISAL imaging process,the content of research is as follow.The fundamental principle of ISAL imaging is presented.Aiming at the problem that the traditional motion model of inversed synthetic aperture radar is unadapted to the imaging application of ISAL,the accuracy mathematical model of ISAL is established.The detailed formula derivation for ISAL imaging process is presented,and the two important steps of focusing and alignment along range direction,motion compensation and imaging along cross-range direction are emphasized,and the final representation of ISAL image is introduced.The jointly compensated imaging algorithm for ISAL high-resolution imaging is proposed.The algorithm consists of two parts,one for global motion compensation algorithm based on Nelder-Mead simplex method,and the other for residual error compensation algorithm based on quasi-Newton method using BFGS formula.The proposed algorithm utilizes Nelder-Mead simplex method to precisely compensate the translational error,rotational error and model error which are existed in the ISAL imaging process,and then residual phase error can be eliminated using quasi-Newton method.After error compensation,ISAL can focus well and realize high-resolution imaging.The related simulation experiment for ISAL imaging is conducted by means of the proposed jointly compensated imaging algorithm.The simulation experiment includes ISAL imaging for both point target and area target with and without noise.The result of simulation experiment shows that the proposed algorithm can implement highresolution 2-dimension imaging and obtaining satisfying image quality.At the meantime,the algorithm is effective for compensating both shot noise and random phase noise.