Scientists develop 3D holograms that you can see, hear and feel

Holograms are no longer just the work of science-fiction, UK researchers claim. 

A team of researchers from the University of Sussex have found a way to create cutting-edge holograms that you can not only see, but also hear and even feel.

These new holographic images can be seen, heard and touched without the need for any virtual reality equipment. The scientists claim they’ve made The scientists published a paper on their new device, Multimodal Acoustic Trap Display (MATD), in the journal Nature. 

The researchers explained that current 3D technology may well be able to create three-dimensional images, but they are slow, short-lived and "most importantly, they are based on operating principles that cannot produce touch and auditory content at the same time.”

The MATD is capable of projecting a coloured butterfly fluttering gently in the air, emojis and other images that are visible without the need for VR (virtual reality) or AR (augmented reality) equipment, simultaneously generating visual, auditory and tactile content, using only acophoresis or acoustic levitation. 

"Our new technology is inspired by older televisions that use a single colour beam scanning along the screen so fast that your brain registers it as a single image. Our prototype does the same thing using a coloured particle that can move so quickly anywhere in three-dimensional space that the human eye sees it as one completed shape," explains Ryuji Hirayama, research leader.

The device works by using ultrasound waves to trap and move a two millimetre-wide polystyrene bead around in midair. The bead traces out an object’s shape in three dimensions while LEDs shine red, green, and blue light on it. The device scans the content in less than 0.1 seconds, which gives the illusion of one single structure. 

"Even though it is not audible to us, ultrasound is a mechanical wave and carries energy through the air. The MATD directs and focuses this energy, which can then stimulate the skin when it is ‘touched’,” Hirayama explains.

Aside from obvious entertainment uses, researchers say this device could be particularly important in fields such as computer science, architecture or biomedicine, as it will allow experts to visualise complex systems in intense detail. It may help scientists to manipulate matter without touching it, along with allowing researchers to mix chemicals without chances of contamination.

Hirayama says: "Operation at frequencies above 40 kHz will allow the use of smaller particles, which will increase the resolution and accuracy of visual content, while frequencies above 80 kHz will result in optimal audio quality.

"More powerful ultrasound loudspeakers, more advanced control techniques, or even the use of multiple particles, could allow for more complex and stronger tactile feedback and stronger audio. Although we have yet to match the communication capabilities of the ‘Rebel Alliance’, our prototype has come even closer and opened up a number of interesting opportunities in the process," concludes Hirayama with reference to Star Wars.

Reference: Ryuji Hirayama et al. ‘A volumetric display for visual, tactile and audio presentation using acoustic trapping’, Nature, (2019), https://www.nature.com/articles/s41586-019-1739-5