27.11.19

Hologram-like device brings objects to life with ultrasound waves

Butterfly
Virtual butterfly: Photo credit, University of Sussex

A team of researchers at the University of Sussex have created a multimodal acoustic trap display (MATD) that creates 3D floating and animated images that can produce sound, visual and tactile (touch) content, similar to sci-fi holograms.

The system traps a particle acoustically and illuminates it with RGB light to control its colour, scanning the display volume and using time multiplexing with a secondary trap to deliver simultaneous audio and tactile content that users can engage with. 

The system demonstrates particle speeds of up to 8.75m per second and 3.75m per second in vertical and horizontal directions. 

The MATD creates visual content by levitating a 1mm radius, white, expanded polystyrene particle as an approximation to a Lambertian surface, using predictive models of acoustic trapping forces, with the twin trap model. 

Dr Ryuji Hirayama, JSPS scholar and Rutherford Fellow at the University of Sussex was the lead author of the project. Hirayama explained:  “Our new technology takes inspiration from old TVs which use a single colour beam scanning along the screen so quickly that your brain registers it as a single image. Our prototype does the same using a coloured particle that can move so quickly anywhere in 3D space that the naked eye sees a volumetric image in mid-air.”



The MATD is also capable of projection mapping, realtime optical tracking and multi-particle and multi-point levitation. 

Hirayama added: “The MATD was created using low-cost and commercially available components, we believe there is plenty of room to increase its capacity and potential. Operating at frequencies higher than 40KHz will allow the use of smaller particles, increasing the resolution and precision of the visual content, while frequencies above 80KHz will result in optimum audio quality.

“More powerful ultrasound speakers, more advanced control techniques or even the use of several particles, could allow for more complex, stronger tactile feedback and louder audio.
“So even though we have yet to match the Rebel Alliance’s communications capability, our prototype has come the closest yet and opened up a host of other exciting opportunities in the process.”