The 3D holograms the researchers displayed are all point-cloud 3D images, which precludes the presentation of a 3D object’s solid body.
A novel technique for producing dynamic, ultrahigh-density 3D holographic projections has been developed by researchers. These kinds of holograms could make it possible to create realistic representations of our surroundings for use in virtual reality and other applications by cramming more details into a 3D image.
Lei Gong, who oversaw a research team from the University of Science and Technology of China, claimed that 3D holograms could display genuine 3D scenes with continuous and fine details.
“Our approach could be used to significantly increase the viewing angles for virtual reality headset-based holographic displays, which would improve the 3D viewing experience. Without a headset, it might also offer better 3D visuals.”
It is necessary to project images with a high pixel resolution onto numerous successive planes, or layers, that are closely spaced in order to create a holographic display of 3D objects that looks realistic.
In order to provide the depth cues that give the hologram the appearance of being three dimensional, it is crucial to achieve high depth resolution.
Three-dimensional scattering-assisted dynamic holography (3D-SDH), a novel technique developed by Gong’s team and Chengwei Qiu’s research team at the National University of Singapore, is described in the journal Optica. They demonstrate that it can accomplish a depth resolution more than three orders of magnitude higher than cutting-edge multiplane holographic projection techniques.
Low axial resolution and high interplane crosstalk, two long-standing bottlenecks in current digital holographic techniques that prevent fine depth control of the hologram and consequently lower the quality of the 3D display, are overcome by our new method, according to Gong.
By enabling more data to be encrypted in the hologram, our method may also enhance optical encryption based on holography. Typically, a spatial light modulator (SLM) is used to modulate the intensity and/or phase of a light beam in order to create a dynamic holographic projection.
However, the quality of current holograms is constrained because only a few low-resolution images can be projected onto separate planes with low depth resolution using current SLM technology.
The researchers combined an SLM with a diffuser, which allows multiple image planes to be separated by a lot less distance without being constrained by the SLM’s characteristics, to solve this issue.
This configuration enables ultrahigh-density 3D holographic projection by suppressing crosstalk between the planes as well as utilising light scattering and wavefront shaping.
The researchers tested a new method to produce 3D reconstructions with a smaller depth interval between each plane. They were able to project a 3D rocket model with 125 successive image planes at a depth interval of 0.96 mm in a single 1000×1000-pixel hologram.
To validate the concept experimentally, they built a prototype 3D-SDH projector to create dynamic 3D projections and compared it to a conventional, state-of-the-art setup for 3D Fresnel computer-generated holography. They showed an improvement in axial resolution of more than three orders of magnitude over their conventional counterpart.
The 3D holograms the researchers displayed are all point-cloud 3D images, which precludes the presentation of a 3D object’s solid body. The researchers’ ultimate goal is to use a hologram to project a group of 3D objects, which will require a hologram with a higher pixel count and new algorithms.