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Augmented reality (AR) displays face persistent challenges in a wide field of view (FOV) and a large depth of field (DOF), while conventional planar waveguide systems suffer from poor ergonomic compatibility and lack diopter correction capability. To address these limitations, we propose a curved-waveguide retinal projection display (CW-RPD) system using freeform optics and freeform holographic optical elements (FHOEs). An ergonomically designed cylindrical curved waveguide (CW) serves as the optical combiner and, together with retinal projection, enables a wide FOV and an extended DOF in a compact form factor. Freeform optical surface in the in-coupler is employed to compensate aberrations induced by multiple off-axis propagations inside the CW, while the FHOE functions as a high-efficiency out-coupling grating with precise control over complex incident wavefronts. In addition, a joint optimization strategy is developed for the waveguide combiner and its exposure system to suppress ghost images caused by repeated diffraction and to control distortion under large-FOV off-axis conditions. A compact cylindrical CW-RPD prototype is demonstrated, achieving a ghosting-free, low-distortion, and high-transparency see-through display with a DOF from 0.25 m to 3 m and a FOV of 61.75°. Furthermore, designs incorporating optical prescriptions are designed to show the advantage and versatility of the system structure. The proposed system opens up a new pathway for the next-generation large FOV and large DOF AR displays.
Lyu et al. (Thu,) studied this question.