Research On Smart Polarization/Intensity Common Aperture Optical Imaging System

In the research of traditional imaging technology,imaging systems mainly collect the intensity and spectral information of the target,such as traditional intensity imaging,multispectral imaging,hyperspectral imaging and other methods.The target information obtained by traditional imaging methods is easily affected by environmental factors.With the development of polarization imaging technology,it has made up for the shortcomings of traditional imaging methods.Polarization imaging technology can obtain information about the polarization characteristics of the target,including the unique attributes of the wave's amplitude,wavelength,and phase.It contains rich details and texture information,and is hard to be restricted by the temperature,the haze and other factors.However,the polarization detection technology also has defects.Due to the attenuation of light energy by polarizing elements,when the target is under an environment with low illuminance,the contrast of the image will decreases,and even the target is submerged.Therefore,target detection under complex background has become a tough research problem that need to be solved urgently.This paper proposes a smart polarization and intensity co-aperture optical imaging system,which not only solves the problem of single information acquisition by traditional imaging methods,but also solves the problem of the loss of target light intensity by polarization imaging technology.The main content and innovations of the paper can be summarized as follows:Firstly,the paper analyzed the imaging error of the polarization imaging system of the sub-focal plane in depth,and defined the crosstalk parameters which is used to established the high-precision polarization vector transmission model under crosstalk conditions.The paper derived a mathematical model of multi-physical coupling interaction including crosstalk,extinction ratio,sensor noise,photoelectron number,target light parameters,and system polarization imaging accuracy.Combine with the least squares method with the constrained matrix,we provide correction parameters for the non-uniform response of the camera.Analyze the sources of errors in the imaging system and investigate the related error correction methods.We set up a polarcam pixel-level polarization camera correction platform to conduct the experiments and correct the collected images for non-uniform noise,blind element noise and instantaneous field of view errors.Secondly,the finite difference time domain software is used to optimize the simulation of the metal nanowire grid array,the core component of the polarization imaging system,by simulating the line width,line height,duty cycle,diffraction distance,material and surface shape of the wire grid.The model explores the influence of key parameters of the wire grid on optical crosstalk,and designs the optimized nanowire grid array.Aiming at the inherent gap between the chip-type nanowire grid array and the focal plane of the detector,a polarization modulation method based on relay imaging is proposed,which uses the conjugate relationship of the bi-telecentric optical path to place the polarization wire grid array on the conjugate point.According to the equivalent medium theory,a large-size polarizing element is matched with a small-size sensor to reduce optical crosstalk while ensuring that the spatial resolution of the system remains unchanged.A large-size relay imaging optical path extinction ratio measurement platform was built,and the Monte Carlo method was used to simulate the influence of optical crosstalk on imaging accuracy under two optical path structures,and the feasibility of the relay imaging polarization modulation scheme was verified.Finally,due to the inherent defect of the polarization imaging method-loss of target light intensity,the background information of the polarization image is blurred and dim,which is not conducive to the analysis of the target.The paper proposes a dual-mode common-aperture optical system,which can realize multiple modes of imaging according to actual needs by flexibly controlling different types of filters to cut into the optical path.Through the fusion of multi-source image information,the complementation of multi-source image information can be realized,which can enrich the amount of information of the image and help improve the target SNR.Based on the polarization image and intensity image obtained in the experiment,this paper applies the scale analysis method to reconstruct the target at the algorithm level,and adopts two different methods based on traditional wavelet and visual saliency to fuse the image to obtain the final enhancement.The image and the evaluation of the two methods prove the practicability of the algorithm in this paper.In summary,this article combines engineering practice to design a smart polarization/intensity co-aperture optical imaging system.On the basis of the existing defocusing plane polarization imaging system structure,the error correction of the optical system is improved.The imaging accuracy of the system;through the optimization of the parameters of the metal nanowire grid unit,the intensity of the optical crosstalk of the system is suppressed;through the design of the modulation scheme and the optical path structure,the new optoelectronic system can adapt to a variety of detection environments;The improvement of the image fusion algorithm improves the accuracy and stability of the algorithm.This series of research provides an important theoretical basis for the multi-mode airborne photoelectric imaging system,and has important theoretical research and practical engineering application value for the development of the airborne photoelectric detection field.