## 4 Conclusions  
In conclusion, a novel near-eye holographic 3D (H3D) display prototype, applicable to holographic AR/MR devices, is proposed and experimentally demonstrated with 360\({}^{\circ}\) full-viewed holographic content to be optically reconstructed as an H3D movie at 30 fps. To achieve a high quality of optical H3D reconstruction, we also proposed an advanced amplitude-modulating encoding scheme (MAO encoding) that is well suited for AM-SLMs, and experimentally verified, for the first time, that the proposed scheme can clearly improve the image quality of monochromatic H3D reconstruction, through quantitative statistical analyses, in comparison with other competitive encodings such as [PERSON]'s encoding and [PERSON]'s encoding. The presented techniques for NEHD we proposed enable an observer to experience the depth cue, a realistic accommodation effect, and high-quality holographic 3D movies at each eye of the user.  
A restriction on the NEHD prototype demonstrated in this study is to cover the monochromatic H3D reconstruction. For the full-color implementation of the NEHD, it is necessary to develop RGB color-matching technologies in real space, including the optical component modification of RGB waveguiding and the RGB image processing of CGHs. Additionally, a field-sequential full color implementation within the presented operation schemes will be accomplished as the next step in the near future. The scopes that we demonstrated in this study did not include searching for the optimum of the parametric factor (\(\varepsilon\)) on the H3D image reconstructed from the proposed novel MAO encoding. For the parametric scaling factor (\(\varepsilon\)), we chose between 1/50 and 1/100, leading to the same behavior results under the sensitivity limit of the DSLR camera we used for H3D image monitoring. To find out the optimal condition of the (\(\varepsilon\)) factor remains another research work, which could be performed by using highly precise tool-based apparatus and measuring techniques. Holographic content treated in this research consists only of 3D objects from a pair of cube shapes without a background image. Thus, to support a hyper-realistic impact on XR environments such as the holographic AR/MR and metaverse applications, researchers are trying to combine holographic 3D object content with a variety of background images.  
We expect to improve the proposed NEHD system towards commercial XR realization through a series of further studies, including the optimization of the parametric factor (\(\varepsilon\)) on the real-like H3D scenes reconstructed from the MAO encoding approach and the holographic measure metrics which we define in the study.  
Conceptualization, M.Y.; methodology and validation, M.Y., H.L.; formal analysis and visualization, M.Y., H.L. and M.K.; writing--original draft preparation, M.Y., H.L; writing--review and editing, H.L., M.K., M.Y., W.S. and Y.Y.; supervision, M.Y., Y.Y.; project administration and funding acquisition, W.S., M.Y. and Y.Y. All authors have read and agreed to the published version of the manuscript.  
This work was partly supported by an Institute of Information and Communications Technology Planning and Evaluation (IITP) grant funded by the Korean government (MSIT) (No.2022-0-00137, XR User Interaction Evaluation and Employing Its Technology). This work was also partly supported by the Korea Research Institute for Defense Technology Planning and Advancement (KRIT) grant funded by the Defense Acquisition Program Administration (DAPA) and Daejeon Metropolitan City (Daejeon Defense Industry Innovation Cluster Project, No. DC2022 RL).  
Not applicable.  
The authors declare no conflict of interest.