Researchers have developed a new method for creating ultra-high-density dynamic 3D holographic projections. This advanced hologram technology is capable of adding a higher level of detail to 3D images, potentially creating more realistic representations of the world for use in virtual reality and a variety of other applications.

“A 3D hologram can represent real 3D scenes with continuous and subtle features,” said Lei Gong, who led the research team from the China University of Science and Technology. “For virtual reality, our method can be used with headset-based holographic displays to significantly improve viewing angles, which will enhance the 3D viewing experience. It can deliver better 3D visuals even without a headset.”

Creating a realistic holographic image involves projecting high-resolution images onto multiple layers close together. This process provides the high resolution critical for depth perception needed to make a hologram appear three-dimensional.

A new 3D scattering dynamic holography approach creates a digital hologram by projecting high resolution images onto closely spaced planes (a), resulting in a more realistic image than traditional holography methods (b).

INSIDE opticalIn the high-impact research journal of Optica Publishing Group, Gong’s team and Chengwei Qiu’s research group at the National University of Singapore describe their new approach, called three-dimensional dynamic scattering-assisted holography (3D-SDH). They show that they can achieve a depth resolution of more than three orders of magnitude than existing multi-plane holographic projection methods.

“Our new method overcomes two long-standing bottlenecks in current digital holography techniques, such as low axial resolution and high interplanetary crosstalk, which impede precise control of hologram depth and thus limit the quality of 3D displays,” said Gong. “Our approach can also improve optical holography-based encryption, enabling more data to be encrypted in a hologram.”

Production of more detailed holograms

Creating a dynamic holographic projection usually involves the use of a spatial light modulator (SLM) to modulate the intensity and/or phase of the light beam. However, current holograms are limited in quality, as current SLM technology only allows a few low-resolution images to be projected onto individual low-resolution planes.

To overcome this problem, the researchers combined the SLM with a diffuser that allows multiple image planes to be separated by a much smaller distance without being constrained by the features of the SLM. Also, by avoiding interference between planes and using light scattering and wavefront shaping, this setup provides ultra-high-density 3D holographic projection.

To experimentally test the concept, they built a prototype 3D-SDH projector to create dynamic 3D projections and compared it to a traditional, cutting-edge Fresnel 3D computer holography setup. They showed that 3D-SDH provides more than three orders of magnitude improvement in axial resolution compared to its traditional equivalent.

The three-dimensional holograms shown by the researchers are three-dimensional images of a point cloud, meaning they cannot represent a solid three-dimensional object. Ultimately, the researchers want to be able to project a collection of hologram 3D objects, which requires a hologram with more pixels and new algorithms.