Samsung scientists have created an interactive, slim-panelled holographic display that increases the viewing angle for 3D videos by 30 times.
The ultra-thin glass prototype could make it easier to incorporate holographic video displays into mobile devices in the future, they say.
Holography is a photographic technique that records light scattered from an object and presents it as three-dimensional, like the hologram of Princess Leia in Star Wars.
But unlike a standard 3D image, a holographic projection allows the viewer to move around and get different perspectives from various positions.
The Korean team have used their display to view a full-screen, 4K interactive video of a swimming turtle that can be viewed from the range of angles and interacted with using a keypad.
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Researchers developed a thin display that means the viewing angle for 3D videos can be increased by 30 times. The addition of a special backlight and light-tilting mechanism to existing compact hologram technology makes this possible in a very slim form
Commercially available holographic video displays have not yet been introduced partly due to their narrow viewing angles, bulky optics and the heavy computing power required.
But the researchers, from the Samsung Advanced Institute of Technology and the University of Seoul, Korea, have used a steering-backlight unit, which comprises a beam deflector, and a holographic video processor to solve these issues.
The beam deflector, which consists of liquid crystal between two sheets of glass, steers the transmitted lights optically like a prism.
It employs a ‘diffractive waveguide’ design, which controls the direction of light waves in a particular direction and saves energy.
‘The steering-backlight unit enables to expand the viewing angle by 30 times and its diffractive waveguide architecture makes a slim display form-factor,’ the research team say in their paper, published in Nature Communications.
Graphic of the beam deflector, which consists of liquid crystal between two sheets of glass, steers the transmitted lights optically like a prism
Photos from the holographic video of the turtle among the coral. All objects in the film are at different depths
‘We suggest that the slim-panel holographic display can provide realistic three-dimensional video in office and household environments.
‘The proposed system will accelerate the adoption of the holographic video for mobile devices.
‘Research is in progress to scale down the volume of the system suitable for mobile phones.’
Holographic displays create a 3D image in space, which can be viewed alongside real objects without causing eye strain.
However, compared to flat images, holographic images and especially videos are more difficult to produce and require a device with many more pixels.
Existing holographic technologies used in thin panels can only produce high-resolution images when viewed from directly in front of the display because they don’t control enough pixels for more angled viewing.
The team developed a thin display that means the viewing angle for 3D videos can be increased by 30 times on existing technologies.
The addition of a special backlight and light-tilting mechanism to existing compact hologram technology makes this possible in a very slim form, which is less than 0.3-inch (1cm) thick.
The prototype includes optical components (beam deflectors, coherent-backlight units, and a geometric phase lens), a holographic video processor board, a spatial light modulator, power connectors, and other components
Combined with a single-chip, custom processor, the authors successfully displayed their full-screen, 4K interactive video of a 3D swimming turtle.
The clip shows images of the holographic video with real objects such as plants, all at different depths, and the user can interact with the turtle in real-time by using a keypad.
Technologies that can produce realistic holograms in slim panels could make 3D displays a more realistic option for use in mobile devices and household electronics.
Holographics use laser light sources, which provide a wider range of colours than LEDs common in today’s VR headsets, phones, computers and TVs.
A common set of colours reproducible on many displays today is called the ‘sRGB colour space’ – which stands for ‘standard red, green and blue’.
This figure illustrates the gamut of colours that are visible in light (outer shape). The sRGB space represents a common set of colours reproducible on many displays today. The outer triangle represents the larger set of colours
sRGB was created by HP and Microsoft created in 1996 to use on monitors, printers and the internet, but it has a limited colour array and captures only a small fraction of the colours that humans can actually see.
Holographics, on the other hand, cover a much larger set of colours, including brilliant luminous shades of all the visible colour spectrum.
Facebook is another tech company working on holographic devices – in July, it revealed a concept for virtual reality lenses less than 0.3 inches (9mm) thick.
Wearers would be able to a set of vivid and saturated colours when playing games or watching films like a ‘brightly lit neon sign’ or the ‘iridescent sheen of a butterfly wing’.
WHAT IS A HOLOGRAM?
‘You’re my only hope’: The scene from the first Star Wars film in which a message from Princess Leia is beamed as a hologram for Obi-Wan Kenobi
Until now, the video hologram has generally been confined to science fiction, the most famous example being the projected image of Princess Leia in the first Star Wars film.
Holography is light presented in what appears to be a three-dimensional form.
It is achieved by recording light that is scattered from an object to build a picture of it in reverse.
A laser beam is split into two before half of it is directed at the object, with whatever is bounced back recorded on recording medium, such as photographic paper.
The other half, a reference beam, is directed at the recording medium to help coordinate a clear image.
Interference between the two beams as they intersect is what creates the imprint of the three-dimensional image – which is then projected for us to see.
However existing systems that project moving holographic images are costly and suffer from severe limitations.
The chief problem lies with devices called spatial light modulators, which direct light to form points in three dimensional space.
With current technology, key elements of display size, viewing angle, frame rate and depth of image are restricted.
Current hologram technology is static, with moving images only achieved through the strobing of images together.
A solution could be found in the form of acoustic levitation, as developed by the researchers at the University of Sussex.