| As the main weapon of the high-tech war, missile is developing constantlytowards high speed and precision. Because supersonic forward-looking conformaloptical system can effectively improve the aerodynamic performance and increasethe flight speed of the missile, it has become the focus at home and abroad. But onthe one hand, the dynamic aberrations with the change of field of view areintroduced, due to the asymmetry in the respective sub-field of view of theconformal optical system. On the other hand, when the supersonic aircraft flies at ahigh speed within the atmosphere, it can produce complicated flow field between thedome and flow which may cause aero-optical effects such as displacement, jitter andblurring of the target image. Both of the above two aspects seriously affect theability of detection, identification and tracking of the system, and become a key thatrestrict the development of supersonic forward-looking conformal optical system. Tosolve above problems, this paper will be divided to four parts:First, the characteristics of degraded image of the supersonic forward-lookingconformal optical system are analyzed. The reason of image degradation isillustrated. The image degradation models of the conformal optical system andsupersonic turbulent flow field are given respectively. The point spread function ofturbulence is simulated by the similar Gaussian function model. This part of work provides a theoretical basis for image restoration and correction of the supersonicforward-looking conformal optical system.Then, the adaptive regularization method for image restoration based onproximity operator splitting is proposed. To reduce the difficulty of solving theproblem, the problem is decomposed into two sub-problems using the theory ofproximity operator splitting method. In order to further improve the computationefficiency of the algorithm, the selection method of the regularization parameter isstudied. The proposed method can adaptively choose the appropriate regularizationparameter. When the regularization parameter is convergent, the peak signal-to-noiseratio of the restoration image reaches maximum and the restored image reaches bestrestoration effect.On the basis of above research, the degraded image of the supersonicforward-looking conformal optical system is restored and corrected. First of all,boresight error along with field of regard ranged from0°to20°are obtained usingray tracing simulation, and the relationship between the boresight error and thegimbal angle is established using quadratic fitting method, thus the boresight errorof the system is corrected; the measurement experiment of boresight error isdesigned and the experimental results show that the boresight error is less than30μmafter correction. Then, in view of the stochastic characteristics of the turbulence, theimage degradation model of the stochastic point spread function is established andthe restoration algorithm using multi-frame turbulence degraded image is proposed.The experimental results show that the proposed algorithm has obvious inhibitoryeffect to the noise and the restoration effect is better than the total variationalgorithm of single frame image. Considering restoration effect and operationefficiency, the frames of the degraded image are usually less than10. Finally, theblurred image induced by astigmatism and coma is restored, and it provides a newtrain of thought for the aberration correction of the conformal optical system.Finally, in order to make the contrast of the restored image more legible,improve the ability of the target identification of the infrared system, the plateau histogram equalization enhancement algorithm based on Parameterized LogarithmicFramework is proposed, and the selection of the model parameters is studied indetail using the image evaluation function EMEE. The hardware platform of imageenhancement experiment is designed, and the restored image has been enhanced.Experimental results show that the algorithm can enhance the image contrastwithout loss of image details. |
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