Research On Image Simulation Of Laser Active Imaging System

Laser active imaging system is mainly used for military tasks such as detection,early warning and tracking.It can realize high-resolution imaging in low illumination complex background and bad weather environment where the passive imaging system is difficult to work normally.In the design,optimization and use of the system,due to the complexity of system parameters and atmospheric environment,the traditional field experiment identification scheme has the problems of high cost,long cycle and insufficient experimental samples.In order to improve the efficiency of system identification and expand the data of imaging results,image simulation can be carried out according to the parameters of laser,target,background,atmospheric environment,optical system and detector to realize realtime dynamic output of imaging results under different identification conditions.Aiming at the practical application requirements of image simulation of laser active imaging system,the goal of this paper is to establish a high realistic,real-time dynamic simulation platform based on physical effects.The atmospheric transmission mechanism,physical effect modeling and coupling,image simulation and evaluation of laser active imaging system are studied in this paper,and the specific work contents are as follows:(1)The multi-dimensional atmospheric transmission mechanism of laser active imaging system is quantitatively characterized and calculated.The atmospheric transmission mechanism is divided into four aspects: attenuation effect,backscattering effect,turbulence effect,and environmental light radiation effect to research respectively.Based on the spectrum,the main reason and calculation method of laser attenuation are obtained by analyzing the absorption and scattering of gas molecules and aerosol particles;According to the laser wavelength and aerosol particle size,type and optical characteristics,the variation law of asymmetry factor and scattering phase function is analyzed,and the scattering energy at any angle is calculated;The spatial distribution of turbulence is characterized by the refractive index structure constant,and the quantitative calculation of turbulence blur and laser speckle effect is realized by combining MTF and phase disturbance principle;The influence of environmental light radiation on active laser imaging is taken into consideration,the irradiance,absorption and scattering of environmental light in different position,time and atmospheric environment are calculated and discussed respectively.(2)The physical effect modeling and coupling method of laser active imaging system are studied.By analyzing the structure of laser active imaging system,the imaging signal transmission link is constructed,and the link is divided into the target background radiation scattering transmission model and the photoelectric system effect model for modeling respectively.The focus is on the spatial distribution of laser energy,the BRDF reflection of the target and background,the transmission effect of the atmosphere,the signal processing of the detector,the MTF and noise of the system.At the same time,according to the spatial structure and imaging principle of laser active imaging system,a physical effect coupling method based on pixel equation is proposed.The imaging results at any pixel are calculated by dividing the task section,matching the imaging pixels,calculating the imaging energy and integrating the scattering effect.(3)The image simulation platform of laser active imaging system is constructed,and the image quality is evaluated.According to the physical effect model and pixel equations,the OGRE 3D image rendering engine and the MFC visual user graphical interface are used to design and construct an image simulation platform to realize the real-time dynamic output of simulation images under different system and environmental parameters.At the same time,the physical effect model and simulation image are used to study the image blur,target background contrast,signal-to-noise ratio and operating distance respectively,and the influencing factors and evaluation scheme of system performance under each index are obtained.