The Application Of Holographic Characterization To The Mechanism Of Photopolymers

At present,with the rapid development of information technology and multimedia technology,the amount of information that needs to be stored,transferred,processed and utilized is rapidly increasing.A storage technology with high capacity and high speed has become ever more crucial.Optical data storage technique has become a hotspot because of its high storage density,high storage capacity,high data transmission rate,short time of searching data and etc.Seeking and studying for the suitable materials has been the focus of optical(holographic)storage technology,and especially for photopolymer materials due to the high photosensitivity,high storage capacity,low cost,high diffraction efficiency,simple preparation,non-toxic,environmental protection and other advantages has aroused widespread concern and research.In this thesis,the study of holographic photopolymer material properties is mainly focused on polyvinyl alcohol/acrylamide(PVA/AA).This thesis provides a deep understanding of the fundamental theory of PVA/AA photopolymer materials,including the method of preparation,photochemical reaction mechanisms,recovery,bleaching and diffusion mechanisms,during and post the holographic recording processes.Based on the understanding,mathematical with chemical methodology are applied to develop a theoretical model that governs these photo-chemical kinetics and photo-physical mechanisms.In this model,the diffusion effect of monomer molecules,the regional effect of photopolymer chains,and the modulation effect of the first harmonic refractive index are also incorporated.By using this model,the numerical results and the experimental data were combined to determine the accuracy of the model in this work.The theoretical model is then used to study the concentration spatial distribution of each reacting component in the material during and after the exposure process.Finally,combining photochemical reaction kinetics of photopolymer material,by reasonably and sensibly varying the recording condition with associated parameters,such as spatial frequency,diffusion rate,exposure intensity,polymerization rate and other factors,the more comprehensive influence on the holographic properties of photopolymer materials mainly including refractive index can be obtained and analyzed,and some significant conclusions are also presented.