Study Of Three Dimensional Imaging Algorithm Based On Interferometric Synthetic Aperture Ladar

Interferometric Synthetic Aperture Ladar(In SAL)is a kind of ladar combining the synthetic aperture technology and the interferometry to get the 3D imformation of targets,which has great research value in the defense and military field.InSAL image processing algorithm can realize the conversion from the interference map to the target elevation information.At present,in order to obtain high resolution,most of the In SAL systems use wavelength modulation error corrections which makes the whole system more complex.And the Interferometric Synthetic Aperture Radar(In SAR)algorithm has low accuracy when is used in In SAL.Optimizing the system is helpful for reducing the volume and weight in the particular enveronment,and the optimization of the algorithms for In SAL is helpful to botain higher accuracy.In the paer,we optimized the In SAL system that solved the current problem of In SAL system in size and weight.And we improved the algorithms so as to improve the imaging accuracy.These optimizations were verified by experiments.At first,this paper summarized and analyzed the domestic and international trends of synthetic aperture 3D imaging.At present,the laboratory verification of In SAL 3D imaging had been realized both at home and abroad,and the related researches had maily focused on the various ways of acquiring target elevation information.In the aspect of algorithm optimization,the research areas included such problems as phase error,ionospheric influence,low unwrapping efficency and etc..Firstly,this paper refering to the problem that in the given application background,the size and weight of the ladar was proposed while most of the In SAL systems were complex,designed a kind of optimized In SAL system structure.The system stucture eliminated the error correction step caused by wavelength modulation and used modulator to load LFM signal.Then we analysed the signal-to-noise ratio and the resolution ratio of the system and the results show ed that it could guarantee the conditions for target resolution and signal-to-noise ratio and reduced the volume and weight of the traditional system.Then,refering to the problem that the traditional In SAR image registration algorithm got a low precision when used in In SAL system,we analyzed the influence caused by the shot noise and thermal noise of the In SAL system and the characteristics of all kinds of registration measures.We studied the average fluctuation function method and spectrum registration method and do the simulation analysis.Futher,the analysis of differences of noise between the In SAL and In SAR was done and we put forward a kind of improved spectrum registration algorithm based on the spectrum registration method and the maximum correlation function method,and the simulation results showed that the improved spectrum registration algorithm improved the registration accuracy 1.43% and spped of registration.Next,refering to the problem that the shot noise and thermal noise affect ed the traditonal phase unwrapping algorithm precision,we analyzed the quality guided unwrapping method,the minimum norm method and the network planning method.We carried out the simulation on the three algorithms and the simulation results show that compared with other two kinds of algorithms,the quality guided phase unwrapping algorithm for In SAL was better.However,the result existed uneven errors.To solve the problem,we proposed quality guided phase unwrapping algorithm based on the regional smoothing.We gave the concrete implementation and simulation experiments of the regional smoothing.The simulation results showed that the regional smoothing quality guided phase unwrapping method could effectively reduce the error of the phase unwrapping to 20.86%.Finally,the experimental system was set up and the verification experiments are carried out.We analyzed the equipment parameters that might affect the experiment,and selected the appropriate instruments and equipment,and built the experimental system based on the optimized InSAL system.The feasibility of the optimized InSAL system was proved by experiments,and the effectiveness of the improved spectral registration algorithm and regional smoothing quality guided phase unwrapping algorithm was proved.