A team from the University of Tokyo presents a practical and cost-effective method for generating holographic images using smartphones, with the goal of simplifying and improving 3D displays for virtual and augmented reality without the drawbacks of laser-based systems. (Artist’s concept).
The full-color 3D visualization method shows potential to enhance augmented and virtual reality experiences.
Scientists have created a method to produce full-color 3D holographic images using smartphone screens instead of lasers. This innovative technique, with further advances, has the potential for augmented or virtual reality displays.
Whether augmented reality or virtual reality displays are used for gaming, education, or other applications, incorporating 3D displays can create a more realistic and interactive user experience.
“Although holography techniques can create a very realistic 3D representation of objects, traditional approaches are not practical because they rely on laser sources,” said research team leader Ryoichi Horisaki of the Univ. from Tokyo to Japan. “Lasers emit coherent light that is easy to control, but make the system complex, expensive and potentially harmful to the eyes.”
In Optica Publishing Group magazine Optics letters, the researchers describe their new method, which is based on computer-generated holography (CGH). Thanks to a new algorithm they developed, they were able to use just an iPhone and an optical component called a spatial light modulator to reproduce a 3D color image that consisted of two holographic layers.
The researchers developed a full-color 3D display method that uses a smartphone screen, rather than a laser, to create holographic images. Their experimental results are shown, in which a continuous transition from the first layer to the second layer is observed. Credit: Ryoichi Horisaki, University of Tokyo
“We believe this method could be useful for minimizing optics, reducing costs, and decreasing potential eye damage in future visual interfaces and 3D display applications,” said Otoya Shigematsu, first author of the paper. “More specifically, it has the potential to improve the performance of near-eye displays, such as those used in high-end virtual reality headsets.”
A more practical approach
Although CGH uses algorithms to produce images, coherent light from a laser is usually required to display these holographic images. In a previous study, the researchers showed that spatially incoherent light emitted by a white-chip light-emitting diode could be used for CGH. However, this setup required two spatial light modulators (devices that control the wavefronts of light), which is impractical due to their expense.
In the new study, the researchers developed a less expensive and more practical incoherent CGH method. “This work aligns with our lab’s focus on computational imaging, a research field dedicated to the innovation of optical imaging systems by integrating optics with information science,” said Horisaki. “We focus on minimizing optical components and eliminating impractical requirements in conventional optical systems.”
First author Otoya Shigematsu is shown in the lab with the optical experiment setup used for the work. Credit: Ryoichi Horisaki, University of Tokyo
The new approach passes light from the screen through a spatial light modulator, which presents multiple layers of a full-color 3D image. While this may sound simple, it required carefully modeling the process of incoherent light propagation from the display and then using that information to develop a new algorithm that coordinated the light coming from the device’s display with a single light modulator spatial
Holographic images from a smartphone
“Holographic displays using low-coherence light could enable realistic 3D displays while reducing costs and complexity,” Shigematsu said. “While several groups, including ours, have demonstrated holographic displays with low-coherence light, we took this concept to the extreme using a smartphone display.”
To demonstrate the new method, the researchers created a two-layer optical reproduction of a full-color 3D image by displaying a holographic layer on an iPhone 14 Pro screen and a second layer on a spatial light modulator. The resulting image measured a few millimeters on each side.
Researchers are now working to improve the technology so it can display larger 3D images with more layers. Additional layers would make images appear more realistic by improving spatial resolution and allowing objects to appear at various depths or different distances from the viewer.
Reference: “Computer Generated Holography with Normal Display” by Ryoichi Horisaki, Otoya Shigematsu, and Makoto Naruse, 14 Apr 2024, Optics letters.
DOI: doi:10.1364/OL.516005
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