3d images

A glass-free technique could enable visual features that do not require special reading or lighting devices

Researchers have developed a new ultra-thin film that can create detailed 3D images visible under normal lighting without any special playback devices. Images appear to float above the film and feature smooth parallax, meaning they can be clearly seen from all angles. With further development, the new glassless approach could be used as a visual safety feature or integrated into virtual or augmented reality devices.

“Our ultra-thin integrated reflective imaging film creates an image that can be viewed from a wide range of angles and appears to have physical depth,” said research team leader Su Shen of Soochow University. in China. “It can be easily laminated to any surface as a label or sticker or embedded into a transparent substrate, making it suitable for use as a security feature on banknotes or credit cards. identify.”

In the magazine Optica Publishing Group Optical letters, the researchers describe their new imaging film. At just 25 microns thick, the film is about twice as thick as household plastic wrap. It uses a technology known as bright field imaging, which captures the direction and intensity of all rays of light in a scene to create a 3D image.

“Achieving glass-free 3D imaging with a wide field of view, smooth parallax, and wide focusable depth range under natural viewing conditions is one of the most exciting challenges in optics,” Shen said. “Our approach offers an innovative way to achieve vivid 3D images that do not cause visual discomfort or fatigue, are easy to see with the naked eye, and are aesthetically pleasing.”

High density recording

Various technical schemes have been studied to create the ideal 3D viewing experience, but they tend to suffer from drawbacks such as limited viewing angle or low light efficiency. To overcome these shortcomings, the researchers developed reflective light-field imaging film and a new algorithm that allows high-density recording of both position and angular light-field information.

The researchers also developed a cost-effective approach to self-release nanoimprint lithography that can achieve the precision needed for high optical performance while using low-cost materials. the other side contains a network of micro-patterns which encodes the image to be displayed.

“The powerful microfabrication approach we used allowed us to create an extremely compact reflective focus, measuring just a few tens of microns,” Shen said. “This allows the burst of light to be densely collected, creating a realistic 3D effect.”

A realistic 3D image

The researchers demonstrated their new film by using it to create a 3D image of a cubic matrix that could be seen clearly from almost any vantage point. The resulting image measures 8 x 8 millimeters with an image depth ranging from 0.1 to 8.0 millimeters under natural lighting conditions. They have also designed and manufactured an imaging film with a floating logo that can be used as a decorative element, for example on the back of a mobile phone.

The researchers say their nanopatterning algorithm and technique could be extended to other applications by creating the nanopatterns on a transparent display screen instead of film, for example. They are also working to commercialize the manufacturing process by developing a double-sided nano-imprint machine that would facilitate the precise alignment required between the micro-patterns on each side of the film.

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