Methods For Enhancing Viewing Angle Of The Glasses-free Three-dimensional Display

As an important part of information technology,display technology is of great significance to meet people's visual requirements.The traditional two-dimensional(2D)display technology cannot contain the depth information of objects,and has been unable to satisfy the human's pursuit of cognition of the objective world.The glasses-free three-dimensional(3D)display technology can provide the depth information of objects and restore the correct occlusion relationship.Therefore,the glasses-free 3D display technology has attracted wide attention from many researchers and enterprises at home and abroad,and is an important development direction in the field of 3D display technology.However,the narrow viewing-angle at this stage is a bottleneck problem that hinders the further development of glasses-free 3D display technology.For example,integral imaging display and the floating 3D display based on the floating lens both have the problem of narrow viewing angle.It cannot satisfy human's pursuit of large viewing angle and high quality glasses-free 3D display technology,and severely hinders the development of glasses-free 3D display technology in various fields.Aiming at the problem of narrow viewing angle,methods of for enhancing viewing angle of the glasses-free 3D display are proposed in this dissertation.The main research contents and innovation points of this dissertation are as follows:(1)Large viewing angle and high quality 3D light field display method based on optical-digital joint optimization algorithmThe traditional integral imaging has the advantages of full parallax and strong stereo perception,but viewing angle and image quality of the display technology need to be further improved.Aiming at this problem of integral imaging,the optical-digital joint optimization algorithm is proposed.Based on the optical imaging theory,aberrations generated by the lens array are analyzed and classified according to the analysis results:those suitable for optical optimization and those suitable for digital image optimization.The lens array is designed and optimized to quantitatively suppress the aberrations suitable for optical optimization to zero or minimum,and a pre-correction algorithm based on Wiener filtering is proposed to suppress other aberrations.With the optical-digital joint optimization algorithm,the viewing angle is increased without increasing the system complexity.Combined with the function of the holographic functional screen to modulate light rays,the proposed display prototype system can effectively suppress the aberrations caused by the lens array,and a high-quality 3D light field display with a 52° viewing angle is realized where 16,900 viewpoints are used.(2)High-resolution and large viewing angle transmission-type floating 3D displayThe floating 3D display can provide a strong sense of immersion and realism.Due to the existence of stray lights and aberrations,it is difficult to achieve satisfactory viewing angle and resolution simultaneously for floating 3D display.Aiming at this problem,a high-resolution and large viewing angle transmission-type floating 3D display is proposed.The stereoscopic display unit is composed of a time-sequential directional backlight module and a liquid crystal(LCD)panel,which can provide 3D images without loss of resolution.A pupil-tracking 3D display method is proposed,which can realize the capture and reconstruction of 3D information based on the real-time pupil spatial positions,and can provide a large viewing angle.Aberrations generated by the floating lens can seriously affect the viewing angle of the entire floating system.In order to solve this problem,a multi-channel and multi-variable 3D image correction algorithm is proposed to obtain floating 3D images with suppressed aberrations.Combined with the pupil-tracking 3D display method,it can realize a large viewing angle and high-resolution floating 3D display.The multi-channel and multi-variable 3D image correction algorithm has universal applicability to floating lenses with different optical structures.Simulations and experiments show that a 60° viewing angle and high resolution transmission-type floating 3D display is realized.(3)Large viewing angle floating three-dimensional light field display based on the spatial data reconstruction algorithmThe traditional floating 3D light field display based on integral imaging and floating lens is can be observed by multiple people.It can restore the original light field distribution,but it has problems such as narrow viewing angle and poor image quality.Aiming at this problem,a large viewing angle floating 3D light field display system based on the light field spatial data reconstruction algorithm is presented.The system consists of a large viewing angle horizontal light field display unit and a floating lens.The light field display unit is composed of a directional backlight module,an LCD panel,a lenticular lens array and a holographic functional screen.By refreshing the coded images and relying on the visual persistence effect of the human eyes,a light field display with a large viewing angle can be realized.At the same time,in order to increase the viewing angle and improve the floating 3D light field image quality of the entire floating light field system,a spatial data reconstruction algorithm is proposed,and the mathematical mapping relationship of the light field spatial data is established.After the coded image is modulated by the optical system,an ideal floating 3D light field image is obtained.In order to further improve the image quality,a weighted optimization algorithm for coded images is also proposed to suppress the 3D image jaggedness caused by the lenticular lens array.Simulations and experiments show that a floating 3D light field display with a viewing angle of 60° is achieved,which can be observed by multiple people,and the image quality is significantly improved compared with the traditional method.