A group from the University of Tokyo have developed a method for adding tangibility to holograms using focussed ultrasonic waves.

This project adds tactile feedback to the hovering image in 3D free space. Tactile sensation requires contact with objects, but including a stimulator in the work space dilutes the appearance of holographic images. The Airborne Ultrasound Tactile Display solves this problem by producing tactile sensation on a user’s hand without any direct contact and without diluting the quality of the holographic projection.