基于柱面计算全息图的360度全视角全息三维显示技术研究

Holographic three-dimensional (3D) display technology can reproduce the full wave-front of 3D objects, and is considered as the ideal technique to realize true 3D display. However, the wide field of view cannot be achieved in the current holographic 3D display technology, only a part of a 3D object can be viewed from a single direction, and it is also difficult to display a 3D object with occlusion effect. All of the above deficiencies make it impossible to display a 3D object with omnidirectional information to be viewed. In this research, a method to realize full-view holographic 3D display of 360 degree based on computer-generated cylindrical hologram (CGCH) is investigated. We mainly focused on the following research topics: 1.A theory model of diffraction from a 3D object to cylindrical hologram is built, and the CGCH is calculated based on this theory model. 2. A method for colorful holographic 3D display is proposed based on single CGCH, by combination of the hologram calculation property and spatial multiplexing technique. 3. An algorithm for optimizing the phase-only CGCH is proposed. Based on this algorithm, the CGCH can reconstruct 3D object with suppressed speckle noise, and the quality of reconstructed 3D object can be greatly improved. Our researches are mainly focused on holographic 3D display by proposing novel algorithms for the CGCH. Based on our research, the problem of narrow field of view and lack of reconstruction information can be solved. This research will introduce a significant progress for realizing holographic 3D display with full field of view and omnidirectional reconstruction from CGCH.

全息三维显示技术能够真实完整地再现三维物体的光波前信息，被公认为是未来实现裸眼真三维显示的理想技术，然而当前的全息三维显示技术无法实现大视场角的观看，只能从单方向观看到三维物体的部分信息，并且很难显示具有前后遮挡信息的三维物体或场景，从而无法实现对三维物体完整信息的全方位显示。本课题研究采用柱面计算全息图来实现360度全视角的全息三维显示。主要内容包括：1. 建立三维物体到柱面全息图的衍射理论模型，并基于该理论计算三维物体的柱面全息图。2.结合柱面全息图的计算特点和空间复用技术实现基于单幅柱面计算全息图的全视角彩色三维显示。3.设计优化算法对相位型柱面计算全息图进行优化，降低其重建的散斑噪声，提高图像的显示质量。本课题通过研究基于柱面计算全息图的全息显示技术，解决了传统全息显示中视场角小、无法显示物体的完整信息等问题，实现了对于三维物体信息的全方位再现。

全息三维显示技术能够在空间中调制和重建完整的光波前信息，被认为是未来实现裸眼真三维显示的最理想技术。然而当前的全息三维显示技术存在视场角小、全息图计算时间长、重建图像存在散斑噪声等一系列待解决的问题。本项目针对以上这些问题，研究了基于柱面计算全息图的全息三维显示方法以及全息显示中视场角的扩大和散斑噪声的消除方法。主要研究成果为：1. 建立了柱面全息图的衍射计算理论模型，提出了一种基于迭代的纯相位柱面全息图生成方法，把彩色图像的红绿蓝分量编码到一张全息图中，实现了基于单张柱面计算全息图的360度彩色全息显示；2. 基于纯相位全息图的复振幅调制技术，实现了对三维波前的相位信息的调控，抑制了由负面干涉带来的散斑噪声，实现了高质量的全息显示；3.采用会聚球面波照明系统，增加了空间光调制器的衍射角，实现了大尺寸大视场的全息三维显示。项目组共发表SCI论文10篇，国际会议口头报告一次，申请发明专利1项，培养青年教师1名、硕士研究生3名。总体来说，项目组顺利完成了计划的科研任务和指标。该项目解决了全息三维显示中的视场角及重建质量等关键问题，为该领域的发展和前瞻性应用提供了有价值的参考。