Star Wars-style holograms move a step closer: Scientists create a floating 3D image that can produce sound and respond to your touch (but no Princess Leia)
- Researchers at University of Sussex, UK, built the ‘hologram’ producing machine
- It uses ‘acoustic levitation’ to create the 3D moving image that can be touched
- Ultrasound is emitted by speakers to lift tiny balls of polystyrene into position
A three-dimensional hologram-like image that users can reach out and touch has been achieved for the first time, using hundreds of silent speakers to levitate tiny particles of polystyrene.
Creating an effect much like the displays seen in science-fiction movies such as Star Wars, the technology, inspired by the movies, is a step into the imagined future.
Researchers at the University of Sussex, UK, built the ‘hologram’ producing machine from 512 speakers set into a plinth above and below where the image appears.
A butterfly moving image is created, appearing to flap its wings as the coloured beams of light are projected onto the moving polystyrene balls
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Ultrasound is emitted by the speakers, lifting tiny balls of polystyrene precisely into position by manipulating the sound waves – to ‘trap the particles acoustically’.
By controlling and shifting air pressure using the speakers the balls can be so quickly manoeuvred to trace a 3D shape that they appear to be a 3D moving image – they float in pockets of low pressure created by the ultrasound.
The tracing of the 3D shape desired by the polystyrene balls must be done in less than 0.1 seconds in order for the visual effect to materialise.
Ryuji Hirayama, who developed the technology after being inspired by the use of holograms or ‘volumetric systems’ in popular culture, called the levitation ‘like magic’.
Researchers created the 3D moving image of a butterfly fluttering its wings along with a rotating Earth.
Although it is not a hologram like the technology imagined in Star Wars when Princess Leia appeals to Obe-Wan Kenobi for help, the new levitation technique offers a wider breadth of possibilities.
True holograms – a physical structure that diffracts light into an image – are created by recording scattered light with a split laser beam on to a recording medium – and then shining light through it to create what appears to be a 3D image.
However with current hologram technology, key elements of display size, viewing angle, frame rate and depth of image are restricted.
The earth appears as a 3D image in the plinth. Because the particles are suspended by sound, they can then make the ‘hologram’ emit sound, and give tactile feedback when you touch it
The effect produced by the researchers, named acoustic levitation, has an element touch and can simulate the feel of skin, as featured in many science fiction films.
Due to the difference in pressure created by the speakers, those who reach out to touch it will ‘feel’ the image – or the area of high pressure.
This could not be achieved with more typical methods used to create a 3D image, including traditional holography (which is the technology imagined by the movies), optophoretics, plasmonics or lenticular lenslets, claims the study.
The team adds that because the particles are suspended by sound, they can then make the ‘hologram’ emit sound, and give tactile feedback when you touch it.
Coloured images can be created by shining various beams of light onto the polystyrene.
The authors of the study concluded: ‘The prototype demonstrated in the work brings us closer to displays that could provide a fully sensorial reproduction of virtual content.’
WHAT IS A HOLOGRAM?
The scene from the first Star Wars film in which a message from Princess Leia is beamed as a hologram (see below) 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.
Princess Leia delivers her call for help
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.
