Lightguide-type folded 4f system for computer-generated-hologram display.

Computer-generated holography (CGH) is a promising approach for realizing head-mounted displays capable of true 3D imaging, but the need for spatial filtering constrains its implementation in compact architectures. This study proposes a method to fold the standard 4f system into a single lightguide, achieving a compact planar configuration. Precise optical design places the Fourier plane on the lightguide surface, enabling direct attachment of spatial filters. The CGH phase distribution is computed utilizing the iterative Fourier transform algorithm, and astigmatism is evaluated through simulation. Measurements show a field-of-view magnification consistent with theory, and images containing depth information demonstrate strong potential for compact near-eye 3D displays.