Investigation Of Holographic Retinal Imaging Algorithm And Optical System

The holographic display has the ability to completely reconstruct the light field of a three-dimensional(3D)scene,and at the same time provides full depth cues to avoid convergence adjustment conflicts,which is an ideal true 3D display.With the development of the Microelectronics information technology,computer technology and liquid crystal on silicon technology,the computer generated hologram(CGH)have gradually replaced the traditional holograms generated by wave interference and played an important role in dynamic holographic 3D display.Because computer holograms are more convenient for production,storage,and transmission,furthermore,they are able to reconstruct virtual objects.However,there are still many problems in the current 3D reconstruction by using computer holograms,which restricts the development and application of holographic displays.This topic introduces the holographic display into the augmented reality near-eye display system,in order to improve the reconstruction quality of the CGH and simplify the optical system of holographic augmented reality display,this paper mainly focuses on the research of holographic display based on a single phase-only spatial light modulator(SLM).It is intended to reduce the amount of calculation and increase calculation speed of CGH and to suppress the speckle noise in the reconstruction process,this paper is going to study the holographic retinal imaging algorithm based on complex amplitude modulation.Moreover,in order to simplify the optical system of the traditional holographic augmented reality display,this paper also makes some research on designing the compact optical structure by use of the holographic optical element(HOE)or the holographic waveguide.Before introducing the main work,this paper firstly summarizes the development history of the traditional holography and the computer holographic display,then introduces the status of 3D displays and holographic displays,meanwhile analyzes some present technical problems of holographic displays.After that,it introduces some important theories of holography,including the classical scalar diffraction theory,some algorithms of CGH for 3D objects,and compares the difference between the amplitude-only hologram and phase-only hologram,which reveals the significance of the complex amplitude modulation in holographic displays.The core content of this paper is about the research of the algorithm and optical system of the holographic retinal imaging display.It mainly can be divided into two parts: algorithm research and optical system research,and these two parts have a common cross section.In the study of algorithms,this paper firstly review two different complex amplitude modulation algorithms for phase-only CGH.Based on the double-phase encoding method,this paper proposed an improved method by introducing a digital pre-filter.This method can avoid the spectrum aliasing that arisen from checkerboard down sampling during the DP encoding method by utilizing a digital pre-filter for the sampled complex field.According to numeral simulations and optical experiments,especially when the pixel pitch of SLM is not small enough or the bandwidth of the complex field is too big,the proposed method is an optimal approach to suppress the background noise due to the spectrum aliasing.This is a simple,effective and without iteration method to improve the reconstruction quality of the holographic display.In the cross section,it is considered by incorporating the human lens system into the imaging optical system,consequently,this paper derived the geometric optical connection in the holographic retinal imaging system to realize the holographic retinal imaging display based on the complex amplitude modulation algorithm.In the study of optical system,the application potential of holographic display in the field of augmented reality was firstly analyzed.Then,this paper respectively made use of the HOE and holographic waveguide to simplify the optical system.In the end,this paper proposed a novel holographic waveguide structure,which attaching the reflective SLM to the holographic waveguide to achieve simplification of the optical system,and the effectiveness of this structure was verified by optical experiments.