Wang Zi, Tu Kefeng, Pang Yujian, Xu Miao, Lv Guoqiang, Feng Qibin, Wang Anting, Ming Hai
Opt Express. 2022 Dec 19;30(26):46450-46459. doi: 10.1364/OE.477816.
Holographic retinal projection display (RPD) can project images directly onto the retina without any lens by encoding a convergent spherical wave phase with the target images. Conventional amplitude-type holographic RPD suffers from strong zero-order light and conjugate. In this paper, a lensless phase-only holographic RPD based on error diffusion algorithm is demonstrated. It is found that direct error diffusion of the complex Fresnel hologram leads to low image quality. Thus, a post-addition phase method is proposed based on angular spectrum diffraction. The spherical wave phase is multiplied after error diffusion process, and acts as an imaging lens. In this way, the error diffusion functions better due to reduced phase difference between adjacent pixels, and a virtual image with improved quality is produced. The viewpoint is easily deflected just by changing the post-added spherical phase. A full-color holographic RPD with adjustable eyebox is demonstrated experimentally with time-multiplexing technique.
全息视网膜投影显示器（RPD）可以通过用目标图像编码会聚球面波相位，将图像直接投射到视网膜上，无需任何透镜。传统的振幅型全息RPD存在较强的零级光和共轭光。本文展示了一种基于误差扩散算法的无透镜纯相位全息RPD。研究发现，复菲涅耳全息图的直接误差扩散会导致图像质量较低。因此，提出了一种基于角谱衍射的后相加相位方法。在误差扩散过程之后乘以球面波相位，并将其用作成像透镜。通过这种方式，由于相邻像素之间的相位差减小，误差扩散的效果更好，并产生了质量更高的虚像。只需改变后加的球面相位，视点就很容易偏转。利用时分复用技术，实验展示了一种具有可调节视场光阑的全彩色全息RPD。
