SUZHOU, China, November 9, 2021 – 3D displays without glasses could transform the wearable electronics industry. However, the limited resolution of display panels in existing 3D displays compromises spatial and angular resolution as well as viewing angle capabilities.
An approach to 3D screens developed by scientists at the University of Soochow distributes display information non-uniformly, depending on people’s viewing habits. The new technique preserves high angular resolution in the central viewing area, while maintaining a wide viewing angle.
In the Soochow team’s approach, spatially varying information is projected as a function of the frequency of observation. Densely packed views are arranged in the center, and sparse views are distributed around the periphery. The approach provides stereoscopic vision with fluid movement parallax to the central view and enlarges the viewing angle to the peripheral view.
To support their display strategy, the researchers developed a large-scale 2D metagratting complex (2DMC) to manipulate views of different shapes. As a view modulator, the 2DMC was able to control the direction of propagation and the irradiance distribution of emerging light from each 2D metarray.
Due to the limited resolution of display panels, today’s 3D displays suffer from a trade-off between spatial resolution, angular resolution, and viewing angle. Inspired by the so-called spatially varying resolution imagery found in the eyes of vertebrates, a team of researchers proposed a 3D display with spatially varying information density. The performance of 3D display without foveolate glasses is shown. (a) Images of Albert Einstein, and (b) whales and lotus leaves, observed in different views with parallax of natural movement and mixture of colors. The numbers in the lower left corner represent the viewing angle of the image. Courtesy of Jianyu Hua, Erkai Hua, Fengbin Zhou, Jiacheng Shi, Chinhua Wang, Huigao Duan, Yueqiang Hu, Wen Qiao, and Linsen Chen.
Researchers designed the 2DMC on a large scale for three purposes: to vary the angular separation of views in different regions; to adapt the irradiance model of each view to eliminate overlap between views and avoid crosstalk; and to avoid gaps between views to ensure a smooth transition in the field of view.
The researchers manipulated the 2DMC to generate the desired radiation patterns; for example, 2DMC generated point-shaped views to provide the highest information density. It can also be used to generate vertically oriented line-shaped views to reduce information density in the vertical direction, while maintaining information density in the horizontal direction. The 2DMC View Modulator can also be used to eliminate crosstalk or increase viewing depth.
By combining views with a fan-shaped irradiance model, the team was able to realize a tabletop 3D display system with varying information density. This provided high spatial and angular resolution in the most comfortable viewing area for people.
“In previous studies, a constant density of information was provided in the viewing angle by views with the same distribution pattern,” the researchers said. “In contrast, we offer a 3D display with spatially varying information density by precisely manipulating the view distribution in a hybrid point / line / rectangle shape. As a result, the information density will be modulated as in the foveal vision of vertebrate eyes. ”
Since the peripheral viewing area is generally less used, the researchers removed the redundant depth information and widened the field of view to a range comparable to that of a 2D display panel.
The researchers also developed a flexible interference lithography system that allowed them to fabricate the view modulator with more than one million pixelated 2D meta-arrays over an area greater than 9 inches.
Using their approach to 3D displays, they demonstrated that a static or video full-color 3D display with a 160 ° field of view could be achieved with display information totaling less than 4K.
The 3D display system has a thin and light form factor that allows it to be integrated into commercial flat screens. The integration possibilities make it potentially useful for portable electronic device applications.
The research was published in Light: science and applications (www.doi.org/10.1038/s41377-021-00651-1).