Making of the Mona Lisa hologram
(Nanowerk News) Holograms are often shown in science fiction as life-size, colorful projections. But what looks like the technology of the future is actually the technology of the present, and has now been used to recreate the Mona Lisa.
In the Applied Physics Review (“Deep Learning Assisted Metasurface Design for Megapixel Acoustic Holograms”), researchers from Tianjin University, Beijing Institute of Technology, Rowan University, University of Missouri, Qingdao University, Shijiazhuang Tiedao University, and Beijing Jiaotong University developed an acoustic metasurface-based holography technique that uses deep learning algorithms to generate and iteratively enhance the hologram of the Mona Lisa.
A hologram is an image created by recording and reconstructing the interference patterns of light or sound waves. They provide realistic and immersive visual or auditory experiences and have applications across the entertainment, medical imaging, and communications fields.
Metasurfaces, or two-dimensional materials made up of arrays of small components such as antennas, can greatly assist holographic processes.
“Metasurface-based holograms work by precisely controlling the phase and amplitude of the waves that interact with the metasurface,” said author Yue-Sheng Wang. “As a result, the outgoing wave at each pixel exhibits a specific amplitude and phase, which produces the desired holographic image by virtue of its interference.”
The team wanted to develop a metasurface holography optimization method to improve efficiency and precision. They use deep neural network-based algorithms to fit antenna-like structures within their metasurface. By iteratively reducing the inconsistencies between the original image and the holographic, they altered the metasurface and created a high-quality hologram.
“We chose to recreate the Mona Lisa as a proof of concept,” said Wang. “It’s so famous that almost everyone knows about it. It is filled with countless smooth and delicate layered transitions, which enhances the softness, blurriness and mystery of the painting. So it’s a great way to demonstrate the effectiveness of our method.”
The holographic method succeeded in reconstructing the Mona Lisa, and in even more detail, her left eye. While the Mona Lisa hologram is two-dimensional, the technique can be extended to create three-dimensional images as well.
“The precise control of sound waves offered by our holography method is essential for advancing non-invasive medical therapies, effective noise control, and optimizing acoustic environments such as concert halls,” said Wang. “This upgrade has the potential to improve quality of life and various applications of the technology.”
The authors believe their technique could revolutionize the field of holography. They plan to find ways to generalize it, make it compatible with 3D printing, and reduce training time.
