Research On Imaging Technology Of Moving Target Through Dynamic Scattering Media

Light scattering is the main factor that restricts optical transmission and influences optical imaging performance.All-optical imaging of moving targets through complex scattering media is one of the most challenging technologies in the optical field.In recent years,speckle correlation imaging through scattering media has attracted more and more researchers' attention.In this thesis,the theoretical basis of speckle correlation imaging is studied,the optical imaging system model is constructed,and the experimental light path is built to verify the feasibility of speckle correlation imaging through scattering media.On this basis,a real-time tracking method for moving targets through scattering media using speckle difference autocorrelation is proposed.The method uses pseudo-thermal illumination and optical memory effect theory to collect two frames of speckles in motion.Subtract two frames of speckle and then perform autocorrelation on the difference.The moving distance of the target is calculated to realize real-time tracking of the target.And the hidden target can be reconstructed by simple processing with phase recovery algorithm.The method has been verified by experiments,and the imaging and tracking of hidden moving targets have been successfully realized.This all-optical imaging and real-time tracking technology for moving targets through scattering media has important application potential in biomedicine and other fields.The speckle correlation imaging method with optical memory effect is susceptible to dynamic scattering medium,while the optical shower curtain effect can overcome the disturbance of scattering medium.For imaging targets through dynamic scattering media,we further propose a speckle illumination imaging method based on the theory of optical curtain effect.Firstly,the theoretical basis of speckle illumination is studied.The speckle illumination theory gives the Fourier spectrum of the target at the order of centimeters after the target.This method can greatly reduce the "far-field" distance,to achieve close distance target image.Accordingly,in combination with the optical shower curtain effect,the scattering medium is used as a projection screen,the spectrum of the target is projected on the surface of the scattering medium,and the camera directly captures the speckle pattern on the surface of the medium.In this thesis,based on the characteristics of speckle illumination,the imaging system is constructed and the experimental optical path is built.A series of pre-processing of the speckles taken by the camera is performed to obtain the spectrum amplitude of the target and substituting it into the phase recovery algorithm to realize the imaging the moving target through the dynamic scattering medium.The structure of speckle correlation imaging based on optical memory effect and speckle illumination imaging system based on optical shower curtain effect are simple and easy to implement,the data processing is not complicated and complementary to each other.The former can be imaged with only one frame of speckle,so it is possible to use a high-pixel mobile phone camera to take a speckle pattern for image reconstruction,which has great application potential on portable devices.The latter can compensate for the inadequacy of speckle correlation imaging,which can not be imaged through dynamic scattering media.In theory,the imaging distance can be extended to any distance.It has great application potential in both biomedical imaging of microtissue cells and astronomy observation of atmospheric turbulence.If the two imaging methods are combined,the scope of application will be wider,and the application field of imaging through scattering media will be further broadened.