Research On The Manipulation Of Structured Light Fields Through Complex Media Based On Digital Micromirror Device

The novel structured light field has important application value in many fields such as optical trapping,optical imaging,optical encryption,optical communication and quantum communication.However,structured beams will suffer from multiple scattering when they encounter complex media during propagation,and their amplitude,phase and polarization structures will be completely destroyed,which hinders the applications of structured beams in complex media.Therefore,this thesis proposes to use digital micromirror device(DMD)to control the incident wavefront accurately and quickly,and then overcome the multiple scattering to construct several structured light fields through the complex media.Moreover,the recognition of object image behind complex media was studied in this thesis.Aiming to solve the problems that the structured light field is completely scrambled by highly scattering and the image recognition through complex media,a series of studies have been carried out in this thesis.The specific research contents are as follows:1.Lommel beams were created through complex media.Following the method of transmission matrix-based point-spread-function engineering,we designed the angular spectrum corresponding to desired Lommel beams,and employed the angular spectrum to filter the transmission matrix of complex media.Our experimental results were in good agreement with simulative and theoretical results.Corresponding spectrums of Lommel beams under different parameters were designed,and Lommel beams with different field distributions through complex media were created.In addition,a DMD was used to quickly scan the created Lommel beams at the two-dimensional output plane,and arrays of Lommel beams were created.This work is beneficial to application of Lommel beams in highly scattering environment.2.The illumination beams of Stimulated Emission Depletion(STED)microscope were created through complex media.We proposed dual-wavelength transmission matrix method,which can simultaneously reshape two incident wavefronts of beams of two wavelengths through same complex medium.Thus,obstacles of highly scattering from complex media were overcome,and the illumination beams of 2D(Two-Dimension,2D)and 3D(Three-Dimension,3D)STED microscopes through complex media were successfully created.The extinction ratio of created beams satisfied actual demand for STED applications.Furthermore,a DMD used to realize fast scanning of illumination beam of 2D STED microscope at output plane,and could switch the illumination beam and STED beam at any time.This work is conducive to the development of STED microscope in complex environment.3.Cylindrical vector beams were created through complex media by calibration of a single scalar transmission matrix.In this way,we proposed a novel scheme to construct cylindrical vector beams beyond complex media.Compared with the previous method,our advantage was that Cylindrical vector beams through complex media were created only by calibrating transmission matrix of a single scalar of complex medium.Moreover,our method had simpler optical system,shorter measurement and calculation time,and lower cost.Further,radially polarized beams,azimuthally polarized beams and generalized cylindrical vector beams were created through complex media by this method.Finally,various cylindrical vector beam arrays through complex media were created.This work will promote applications of cylindrical vector beams through complex media.4.Edge enhancement of objects through complex media by using transmission-matrix based spiral phase contrast imaging.This method could reconstruct the edge enhancement image of object from the corresponding speckle image of the object.In order to verify our method,the proposed technique was first demonstrated by imaging two digital objects.The edge enhanced images of both amplitude and phase objects were obtained,and the correlation coefficient between the reconstructed edge enhancement images and the theoretical edge enhanced image was calculated to be～0.9.In addition,it was noted that the fidelity of the edge enhancement images could increase with increase of ratio of output mode to input mode.Finally,we applied this technique to image a real amplitude object and a real phase object,further confirming the feasibility of our method.This work provides a new scheme for detecting object information through complex media.In this thesis,the proposed methods and technologies of creating multiple structured beams through complex media could effectively promote applications of these structured beams in highly scattering environment.The structured beams created through complex media are expected to be used optical manipulation and imaging in deep tissue in the future,and also promote the development of optical communication,information encryption and other fields in highly scattering environment.The proposed technology of edge enhancement for objects through complex media also provides a new scheme for image recognition of objects in highly scattering environment.