The Key Technology Research Of The Tabletop Light Field Display

In the age of information,the novel display technology is constantly innovating and perfecting.In recent years,benefitting from the rapid development of computer technology and three-dimensional(3D)display technology,massive 3D date are easily available.However,the previous 3D display technology could not meet people's expectation due to the various defects.The tabletop light field display is considered to be the next generation of 3D display technology with the most potential and application propect.It can employ the light field display technology to reconstruct the 3D scenes and dynamic information in the way of tabletop display,which can greatly improve the speed and efficiency of information processing.Unfortunately,the current tabletop light field display still suffers from some problems,such as low viewpoint density,small viewing angle and limited depth of field,which limit its application and development in various fields.Therefore,this dissertation focuses on the above problems to achieve high quality tabletop 3D light field display effect.The main research content and innovations of this dissertation are listed:(1)The tabletop light field display method with high viewpoint density and low crosstalk based on viewpoint horizontal modulationKey point 1:Due to lack of the accommodation stimulus for the monocular vision in the conventional tabletop stereoscopic display,the convergence distance of binocular vision is inconsistent with the accommodation distance of monocular vision,which leads to convergence-accommodation conflict.To solve this problem,a tabletop 3D light field display system with narrow cylindrical lens array and the vertically-diffused holographic functional screen is designed to realize viewpoint horizontal modulation,and a multi-subnuit joint coding algorithm is proposed,which can realize the side-by-side interpolation arrangement of ultra dense viewpoints in space.The simulation and experimental results show that the proposed method can realize the dense arrangement with the viewpoint density of 1mm-1,and at the same time,it can provide four viewpoints for one eye to meet the accommodation simulation,thereby eliminating the convergence-accommodation conflict,and finally realizing a clear 3D image with natural depth cues.Key point 2:The light emitted from adjacent pixels of the LCD panel will cause serious crosstalk between viewpoints due to the conventional scattering backlight.To solve this problem,the vertically-collimated programmable directional backlight is designed to suppress scattering light effectively,and the eye tracker is employed to provide smooth motion parallax for observer in a time-division multiplexing manner.Finally,the low crosstalk between viewpoints is achieved.In the experiment,352 viewpoints are used to achieve high quality 3D images with the crosstalk of less than 6%in the viewing angle of ±20°.(3)The full parallax tabletop light field display method with wide viewing angle and high viewpoint densityKey point 3:The conventional light field display based on integrated imaging is difficult to simultaneously achieve wide viewing angle and high viewpoint density to display high quality tabletop 3D display effect.To solve this problem,a space-multiplexed voxel screen based on projector array and holographic functional screen is designed to replace the conventional liquid crystal panel.This method can not only enlarge the viewing angle while ensuring high viewpoint density,but also eliminate the image flipping and reduce the influence of aliasing phenomenon on the 3D display effect.This method improves the viewing angle of the display system from 32° to 96°,and 44100 viewpoints are reproduced to reconstruct the high quality 3D scene with continuous smooth parallax.(4)The method of depth of field enhancement for tabletop 3D light field display with 360° ring-shaped viewing angle.Key point 4:Due to the conflict between the focusing ability of the lens array and the intersection characteristics of the light in the display system,the facet braiding phenomenon is produced,which limits the depth of field and reduces the stereoscopic effect of the display system.To solve this problem,this dissertation analyzes the imaging characteristics of the tabletop 3D light field display system based on conical lens array,and proposes the viewpoint fitting coding optimization algorithm based on human eye positon to reduce the influence of the facet braiding,and improve the depth of field in the ring-shaped viewing angle.By means of this method,the clear depth of field range of the display system is increased from 13cm to 15cm,and the visualization effect of the 3D imaging is enhanced.