Fig. 1. Principle of RPD.（a）RPD based on SLM；（b）RPD based on LBS.

Fig. 2. Eyebox expansion of RPD using beam splitter array（a），steering mirror（b）and LED array（c），respectively.

Fig. 3. Crosstalk problem with a narrow viewpoint spacing（a）and blank image problem with wide viewpoint spacing（b）in the RPD with multiple viewpoints.

Fig. 4. RPD based on HOE.（a）LBS image source beam converged by lens HOE；（b）SLM image source beam converged by lens HOE.

Fig. 5. （a）Point light array produced by lens array HOE；（b）Multiple converging beams are recorded to a single HOE.

Fig. 6. （a）Reflective PVG；（b）Transmissive PVG.

Fig. 7. （a）Principle of holographic RPD；（b）Eyebox expansion of holographic RPD using multiple spherical wave encoding method；（c）Eyebox expansion of holographic RPD using conjugate wavefront encoding method.