Researchers from the University of Shanghai for Science and Technology (USST) introduced a one-step method to generate holograms in real time. This approach to creating computer-generated holograms (CGH) could provide a practical solution to create immersive 3D visualizations, opening a path to adopt holographic displays in diverse industries and applications. The method uses a Split-Lohmann lens-based diffraction model based on a Fourier holography system between an RGB image and the hologram plane. The model enables rapid synthesis of 3D holograms through a single-step, backward propagation calculation. The light-wave propagation from the RGB image to the hologram is modulated by a predesigned, depth-dependent, virtual Split-Lohmann lens phase. The specially designed phase modulation enables accurate reconstruction of 3D scenes with precise depth perception. The resulting CGH appears to reconstruct 3D scenes with accurate accommodation abilities across the display contents, and displays image content with spatially varying focal lengths, to provide a true 3D display experience with dense sampling of focal planes. A full-color holographic near-eye display uses an eyepiece lens to magnify 3D images, which are then recorded by adjusting the focus of the camera lens. A hologram is then generated quickly using a Split-Lohmann lens-based diffraction algorithm. Courtesy of Chang et al., doi 10.1117/1.APN.3.3.036001. The Split-Lohmann approach to CGH operates with a fixed computation time that is predetermined by the hologram size and independent of the depth quantization levels. The ultralight computational footprint enables a high-resolution CGH to be created at real-time speeds using commodity hardware. The high-speed, diffraction simulation-based CGH generation method requires only one-step diffraction calculation from the RGB depth image to the hologram. In contrast, conventional diffraction-based methods require repetitive diffraction calculations from point clouds or layer images. This requirement increases computational complexity, making conventional methods impractical for real-time applications. Unlike conventional methods, which are likely to face computational bottlenecks, the new approach to CGH generation ensures consistent computation speed regardless of the depth sampling density. The researchers assessed the proposed method for CGH creation in simulations and in an experimental prototype system. They demonstrated that the new approach can generate realistic 3D holographic displays with accurate depth perception. Split-Lohmann computer holography, which provides the ability to sculpt 3D light waves associated with different spatial locations in real time, can potentially be used for systems beyond holographic 3D displays. Potential applications include the use of this approach to multitrap optical tweezers and for neural photostimulation. Holographic displays are a promising path to achieving lifelike 3D reproductions with continuous depth sensation for the entertainment, medical imaging, and virtual reality fields. The work of the USST team advances CGH technology and may enable CGH to be seamlessly integrated into various applications that require immersive 3D visualization. The new approach also offers a practical solution for creating immersive 3D visualizations without the computational limitations of traditional methods. It can significantly reduce computational overhead, while maintaining high-quality 3D visualization. The research was published in Advanced Photonics Nexus (www.doi.org/10.1117/1.APN.3.3.036001).
