Research On Underwater Polarization-based Ghost Imaging

The ocean has extremely important political,economic and military significance.As an important means and tool for understanding,exploiting and utilizing the ocean,underwater target detection plays an important role in deep sea resource development and marine scientific research.As a commonly used underwater detection technology,optical detection technology has the advantages of high resolution target,high information content and intuitive image.While water attenuation and backscattering are the main factors that limit the detection distance,resulting in a decrease in the quality of the target image.As a new imaging method,ghost imaging technology has the ability to image through optical scattering media,which can improve the detection range and quality of underwater optical detection technology.In this paper,underwater ghost imaging research is carried out.The basic principles of ghost imaging and computational ghost imaging are introduced.The traditional ghost imaging reconstruction algorithm and reconstruction algorithm based on compressed sensing are studied,and the two types of algorithms are compared,the results show that the reconstruction algorithm based on compressed sensing is much better than the traditional ghost.The influence of backscattering on underwater ghost imaging is studied.It is pointed out by theory and experiment that in ghost imaging the backscattered light will be superimposed on the object signal to form a strong background noise,which resulting in a greatly reduce on signal-to-noise ratio and contrast of image,and even floods the signal,and then a forward model of underwater ghost imaging is established.After that,according to the polarization-preserving characteristics of backscattered light,it is proposed to eliminate the backscattered light by using two orthogonal polarizations,and establish a polarization-based underwater ghost imaging model.A mathematical solution algorithm is given.According to the principle of underwater polarization ghost imaging,an underwater polarization ghost imaging experimental scheme is designed and an underwater polarization ghost imaging experimental platform is built.The experimental platform mainly includes high-speed spatial light modulator,projection system,data acquisition card,photomultiplier tube,linear polarizing plate and LED light source.Based on Labview,the experimental platform control software is written to realize the synchronization of the spatial light modulator and the photomultiplier tube.The underwater ghost imaging experiment is carried out using the experimental platform.Experimental data are collected in 7 kinds of different water turbidity,Structural Similarity(SSIM)are used to analyze the reconstruction results in this paper.The experimental results show that the underwater polarization ghost imaging algorithm can suppress backscattering and improve the image quality effectively.