Large screen size transparent display using spectrum expanded light field holograms

Holographic displays have the potential to reconstruct natural light field information, making them highly promising for applications in augmented reality (AR), head-up displays (HUD), and new types of transparent three-dimensional (3D) displays. However, current spatial light modulators (SLMs) are constrained by pixel size and resolution, limiting display size. Additionally, existing holographic displays have narrow viewing angles due to device diffraction limits, algorithms, and optical configurations. To overcome these obstacles, we propose a transparent large-size light-field holographic display system. This system utilizes a spectrum-expanded light-field holography algorithm that decomposes the light field in the spectrum domain according to each viewing angle. The spectrum is expanded by a factor of 3. The proposed algorithm widens the viewing angle of the holographic display and utilizes the full spectrum of the display device to support smooth motion parallax as well as the natural depth of field of the light field. Furthermore, we further enlarge the display size by introducing waveguides, and optimize the far-field display performance of the waveguide. The display size is enlarged to 100 mm compared to the general method. The extended spectrum enhances the diffraction angle on the waveguide's grating, resolving content discontinuity in far-field views. The proposed method allows for a more vivid perception of light fields with motion parallax and depth effects on a large transparent screen.