Author Affiliations
Abstract
1 Jiangsu Key Laboratory for Opto-Electronic Technology, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China
2 Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China
In liquid crystal spatial light modulator (SLM)-based holographic projection, the image is usually displayed at a distant projection screen through free space diffraction from a computer-generated hologram (CGH). Therefore, it allows for removing of the projection lens for the sake of system simplification and being aberration free, known as the “lensless holographic projection”. However, the maximum size of the optical projected image is limited by the diffraction angle of the SLM. In this Letter, we present a method for the implementation of image magnification in a lensless holographic projection system by using convergent spherical wave illumination to the SLM. The complete complex amplitude of the image wavefront is reconstructed in a lensless optical filtering system from a phase-only CGH that is encoded by the off-axis double-phase method. The dimensions of the magnified image can break the limitation by the maximum diffraction angle of the SLM at a given projection distance. Optical experiment results with successful image magnification in the lensless holographic projection system are presented.
090.2870 Holographic display Chinese Optics Letters
2018, 16(10): 100901
1 东南大学 电子科学与工程学院, 南京 210096
2 江苏新广联半导体有限公司, 无锡 江苏 214192
出一种适用于增强现实的视网膜显示技术, 利用一个相位型空间光调制器结合计算机全息图算法, 实现了直接在视网膜上进行全息重建。首次从理论出发, 给出了相位型空间光调制器输入相位与眼球前平面光场的计算关系, 讨论并比较了基于GS的全息图计算方法和基于双相位编码的复振幅调制全息图计算方法的特点, 采用复振幅调制, 全息重建中的散斑噪声得到抑制。仿真和实验结果验证了应用于视网膜全息成像的计算机全息图算法的有效性。实验证明, 该方法能够利用一个纯相位空间光调制器在眼球里进行多平面的无散斑全息重建, 同时在视网膜附近重建振幅信息, 使得眼睛聚焦在某个平面时, 该平面的图像能够恰好投影在视网膜上。整个过程模拟了自然场景中人眼调焦和观察的过程, 不同于双目视差的三维显示方法, 文章提出的视网膜显示技术是一种真三维全息重建, 不存在视觉辐辏调节冲突。
全息显示 复振幅调制 增强现实 holographic display complex modulation augmented reality
Author Affiliations
Abstract
1 Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China
2 Key Laboratory for Opto-Electronic Technology of Jiangsu Province, Nanjing Normal University, Nanjing 210023, China
A method is proposed to realize accurate spatial complex modulation based on the spatial cross-modulation method (SCMM) via a phase-only spatial light modulator. The conventional SCMM cannot achieve high quality reconstruction, especially when the diffusion ratio is small. We propose an iterative algorithm in the calculation of a computer-generated hologram to implement accurate complex modulation. It enables us to generate a high quality reconstruction under a small diffusion ratio. The feasibility of the method is verified by both a numerical simulation and an optical experiment.
090.2870 Holographic display 090.1760 Computer holography 110.7348 Wavefront encoding Chinese Optics Letters
2017, 15(2): 020901
