Computer scientists at the University of Bristol have developed invisible 3D object holograms in mid-air that can be felt and seen using ultrasound, which could one day be used to help surgeons "feel a disease" in a CT scan.

The UltraHaptics technology works by pulsing high-frequency sound waves from tiny speakers that exert pressure on a person's hand to create the feel of haptic holograms, i.e. an object that can be touched by applying forces, vibrations or motions to the user.

The system also makes use of a Leap Motion sensor that can track the position of a person's hand in order to decide where in the air to create the object.

Their research, entitled "Rendering volumetric haptic shapes in mid-air using ultrasound", is published in the journal ACM Transactions on Graphics (TOG).

In order to be able to actually see the objects, the researchers projected the sound waves onto a thin layer of oil, and the depressions of the shapes and how the shapes move can clearly be seen on the surface.

Several different types of shapes including spheres and pyramids have been successfully created and although the objects currently being projected might not be perfect, the researchers say that it is enough to create touchable 3D holograms, as the brain has the ability to bend what it sees and feels to create a complete picture of the item.

It is also possible to improve the resolution of the object by adding more tiny speakers.

Video courtesy of Bristol Interaction and Graphics group - University of Bristol