Benjamin Long and colleagues at the University of Bristol have developed invisible 3D object holograms that can be felt and seen in mid-air using ultrasound. Potential uses include helping surgeons “feel” the differences between materials in a CT scan to diagnose disease, or, combined with a VR headset, to rehearse surgeries.
High-frequency sound waves are pulsed from miniature speakers that exert pressure on one’s hand to create the feel of haptic holograms. A Leap Motion sensor tracks hand positions to decide where in the air to create the object. Sound waves are projected onto a layer of oil, and shape depressions and movements can be seen on the surface.