罢辞诲补测鈥檚 holograms cannot create interactive 3D shapes like the ones we see sci-fi movies, but a new method that uses a single particle to trace out a floating picture brings that one step closer to reality.
鈥淲e鈥檝e all been deceived when it comes to holograms,鈥� says at Brigham Young University in Utah. 鈥淓ven if holograms get as good as they could possibly be, they鈥檙e fundamentally limited and incapable of creating a Princess Leia-like image that floats in space, far from its projected aperture, that you can walk around and look at from all angles.鈥�
Now, Smalley and his colleagues have found a way to form a three-dimensional image from a single fast-moving particle levitating in the air.
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Their method works by trapping a particle made of cellulose inside a laser beam invisible to the human eye. The laser is focused through a lens with imperfections such that the resulting beam has pockets of darkness surrounded by bright laser light.
The researchers shine the beam on a pile of microns-wide particles to capture one inside a pocket of darkness. If the particle starts to move out of the darkness, it hits bright light and one side heats up. The resulting temperature difference between the two sides of the particle creates thermal repulsion and propels it back to the centre of the dark spot.
Shape of things to come
The laser beam is reflected through a mirror that swivels, directing the particle trapped inside to trace a shape. We can see the image because the particle is illuminated by a separate coloured light. To create a relatively simple image, the particle must move faster than 15 centimetres per second. The more complex the image is, the faster the particle has to flit around.
For now, Smalley鈥檚 team can only make simple outlines about a centimetre across. Anything larger and the particle won鈥檛 be able to move fast enough to trick your eyes into seeing a smooth image. More complex images, like a full-colour picture of Earth, just look like a moving dot to the naked eye. The only way to see them is with a camera set to a long exposure.
Smalley says the system could be improved by using multiple lasers instead of just the one, so that each beam doesn鈥檛 have to move quite as fast to build the image. 鈥淚f we had the resources, we could scale it up now,鈥� he says.
Once we can trace larger pictures, the potential applications are varied. 鈥淭here are an awful lot of tasks where we need to visualise in 3D, and we鈥檙e not very good at thinking in 3D,鈥� says at the University of Derby in the UK.
Blundell says a volumetric display could be useful for all sorts of tasks that require spatial analysis, from controlling swarms of drones to performing complicated surgeries.
鈥淚f a practitioner could see just the cross section of the artery as he or she is guiding a catheter through the 3D path, that could improve surgical outcomes,鈥� says Smalley. 鈥淚t wouldn鈥檛 take much 鈥� it would just take images of a few rings to make sense of the artery.鈥�
If this technology can be scaled up, the next step is to figure out how we might interact with the images without disturbing them. For instance, a gentle breeze is often enough to push the particle out of its beam and destroy the image.
It will be five to 10 years before you can buy such a display for yourself, says at Swansea University in the UK. Add motion sensing and haptic feedback to make it feel like you are touching and moving a physical object and a holographic workshop like Tony Stark鈥檚 might actually be possible.
Nature
Read more: Have we found evidence that we live in a holographic universe?
