【作者】 刘辉；

【导师】 郑臻荣； 李海峰；

【作者基本信息】 浙江大学 ， 光学工程， 2012， 硕士

【摘要】 随着信息社会日新月异的发展,头盔显示技术已在诸多领域展示出巨大的应用价值和发展潜力。其中,穿透式头盔显示一直以来都是头盔显示技术研究的重点。基于护目镜成像是目前主流的穿透式头盔显示技术,但是其光学系统笨重且占据着头盔内大量空间。为了适应头盔显示器轻型化、小型化的发展趋势和要求,技术界提出了采用全息平板波导和半透膜平板波导进行显示的新方法。由于相关技术不成熟,全息平板波导显示目前只能实现单色、低分辨率显示输出；半透膜平板波导显示虽然能够实现彩色显示,但是传统结构会造成严重的鬼像问题。文中针对全息波导显示的相关技术及原理进行深入分析和研究。首先,分析了全息光栅空间频率、视场、波长、波导尺寸等参数之间的关系。然后,从出瞳直径、出瞳距离、工作距离、调制传递函数、点列图、场曲和畸变等入手,进行了光学系统的优化设计。最后,设计完成了一套采用640nm和532nm半导体激光器作为光源的全息头盔显示系统。该系统能够实现20.2°水平视场和15.2°垂直视场大窗口显示,窗口中心区域的镜目距大于25mm。由于实验条件不足,文中针对上述的理论分析进行了部分实验验证。通过计算分析,传统结构的半透膜平板波导显示存在严重的鬼像问题。本文就该问题提出了改进方案,设计了一套三层波导结构的半透膜平板波导显示系统。该系统能够实现16°水平视场和12°垂直视场大窗口显示。根据系统的设计参数,搭建了实验平台。由于合理的半透膜反射率的设计,系统实现了背景环境的高透过率以及显示色彩的一致性。同时,实验结果表明这种改进型结构能够实现避免传统结构导致的鬼像问题。更多还原

【Abstract】 With the rapid development of information society, head-mounted display (HMD) has shown great values and development potential in many fields. The see-through display system has been the focus of the study in HMD. Imaging based on goggles is the main technology of see-through HMD. However, its optical system is bulky and occupies much space inside the helmet. In order to meet the trends and requirements of lightweight and small size, display based on planar holographic waveguide and planar transparent-filmed waveguide are proposed as new methods for HMD. Due to immature technology, only low-resolution quasi-monochromatic image can be acquired in display based on planar holographic waveguide. Although planar transparent-filmed waveguide can achieve color display, the traditional structure will cause ghost images.In-depth research on the technology and principles of display based on planar holographic waveguide is conducted in the paper. Firstly, correlation of grating’s spatial frequency, FOV, wavelength, waveguide’s size and other parameters are analyzed. Secondly, considering exit-pupil diameter, exit-pupil distance, working distance, MTF, spot diagram, field curvature, distortion and so on, optical system is optimized. Lastly, a set of holographic HMD’s system is designed with 640nm and 532nm LDs as light source. The system can achieve 20.2°horizontal FOV and 15.2°vertical FOV. It also has a large eye box and over 25mm eye relief. Limited by the experimental conditions, only partial experiment is carried out to verify the theoretical analysis.Through computational analysis, there will be serious ghost images in traditional structure of display based on planar transparent-filmed waveguide. Improved program is proposed to eliminate ghosts. A set of system with tri-layer planar transparent-filmed waveguide is designed. The system can achieve 16°horizontal FOV and 12°vertical FOV, and a large eye box. With the system parameters, an experimental platform has been built. Due to reasonable reflectivity of transparent films, a high-transmittance background and color conformity are gained. Meanwhile, experimental results show that the improved structure can avoid ghost images caused by traditional structure of planar transparent-filmed waveguide.更多还原