Study Of The Light Field Manipulation And High-resolution Imaging Through A Scattering Medium

Nowadays,scattering imaging has become a hot topic in scientific research.Most of the scattering imaging studies have focused on scalar optical fields,such as single-point focusing,multi-point uniform focusing,and vortex focusing.However,the generation and manipulation of super-resolution vector light fields with complex polarization state distribution after passing through scattering media is still an area to be explored.Due to its novel characteristics and special polarization state distribution,the vector light field has been widely used in the fields of optical capture,optical communication,optical detection,and three-dimensional focal field modulation.At present,the propagation dynamics of vector light field in a scattering medium,especially the generation of high resolution vector light field through scattering medium,has become a hot topic in this field.Therefore,in this paper,the scattering problem of scalar and vector light field propagating in a scattering medium is studied theoretically and experimentally by calculating the propagation matrix of scattering medium and the generation method of high resolution imaging after light field passing through scattering medium.This work will provide a new method and means for the generation and manipulation of high resolution(scalar)vector light field in scattering environment.The work content is as follows:(1)Theoretical derivation of the generation of high resolution light field after passing through scattering medium by optical matrix method.The scattering speckle theory and the mathematical expression for scattering speckle are introduced.The theory of light transmission in scattering medium and the characterization methods of scalar transmission matrix(TM)and vector transmission matrix(VTM)are analyzed.The theory for measuring the scattering medium TM of scalar light field and realizing the high resolution imaging of scalar light field by the scattering medium are described.(2)The generation of high resolution single and multipoint foci on the output surface for the scalar light field passing through the scattering medium.An experimental device for measuring scalar TM was built,and the scattering medium TM with matrix size of 32~2×100~2was measured experimentally.By using TM and phase conjugation technique(OPC),the single point focusing of the scalar light field at different positions on the output surface through the scattering medium is realized.Then TM is optimized by the Tikhonov regularization method to obtain the mean square error operator,and the multi-point uniform focusing on the output surface is realized with the mean square error operator.(3)Measurement of VTM of scattering medium and the generation of high resolution single and multi-point foci with different polarization states.The polarization stateof vector light field is characterized based on Jones matrix.The generation method of vector light field with 4f system is described.A new method for measuring VTM based on holographic grating and phase shift method is proposed.The experiment setup for measuring VTM is simple and easy to operate,and VTM measurement can be completed without moving optical devices,which greatly reduces the phase error of VTM measurement.The VTM with a matrix size of 4×32~2×100~2were measured,and the generation of single and multi-point foci with different polarization states(left circular,right circular,horizontal and vertical linear polarization states)is realized by the experiment setup.(4)The high resolution vector light field and the new type of twisted vector light field in the output plane after passing through the scattering medium are generated experimentally.The high resolution vector light field is generated experimentally with the scattering medium by the vector light field scattering imaging system and OPC technology.The scattering medium VTM is obtained by using holographic grating and four-step phase-shift method with a pair of orthogonal circular polarization vectors(left and right circular polarization bases).The high resolution vector light field with different polarization state distribution(azimuthally-variant,radially-variant,and both radially-and azimuthally-variant)and the new type of twisted vector light field are generated experimentally in the output plane with the scattering medium by the measured VTM.