Touchable Holography .........they managed to get this done

Research in Japan is doing some great stuff. My previous post was on the 3D cubes and now this. Details from their work are below and might be a little technical but just look at the video and you'll be amazed (and beyond). This is simple (to some extend) and very cool.

Recently, mid-air displays are attracting a lot of attention in the fields of digital signage and home TV, and many types of holographic displays have been proposed and developed. Although we can "see" holograhpic images as if they are really floating in front of us, we cannot "touch" them, because they are nothing but light. 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.




1 Introduction

Mid-air displays which project floating images in free space have
been seen in SF movies for several decades [Rakkolainen 2007].
Recently, they are attracting a lot of attention as promising tech-
nologies in the field of digital signage and home TV, and many
types of holographic displays are proposed and developed. You can
see a virtual object as if it is really hovering in front of you. But
that amazing experience is broken down the moment you reach for
it, because you feel no sensation on your hand.

Our objective is adding tactile feedback to the hovering image in
3D free space. One of the biggest issues is how to provide tactile
sensation. Although tactile sensation needs contact with objects by
nature, the existence of a stimulator in the work space depresses the
appearance of holographic images. Therefore some kind of remote-
controllable tactile sensation is needed. That is achieved by our
original tactile display [Iwamoto et al. 2008]. The following paper
explains the technologies employed for a “Touchable Holography.”

2 Principle

2.1 Holographic Display

We use “Holo [Provision 2009],” a holographic display which pro-
vides floating images from an LCD by utilizing a concave mirror.
The projected images float at 30 cm away from the display surface.
A user can get near to the image and try to touch it. Of course, his
fingers pass through it with no tactile sensation.

2.2 Tactile Display

“Airborne Ultrasound Tactile Display [Iwamoto et al. 2008]” is a
tactile display which provides tactile sensation onto the user’s hand.
It utilizes the nonlinear phenomenon of ultrasound; acoustic radia-
tion pressure. When an object interrupts the propagation of ultra-
sound, a pressure field is exerted on the surface of the object. The
acoustic radiation pressure P [Pa] is written as
P = E (1)
where E [J/m3] is the energy density of ultrasound.  [-] is a con-
stant ranging from 1 to 2 depending on the reflection coefficient
at the object surface. The acoustic radiation pressure acts in the
same direction of the ultrasound propagation. That is, roughly say-
ing, the ultrasound “pushes” the object. Eq.(1) suggests that the
spatial distribution of the pressure can be controlled by using wave
field synthesis. When the tactile display radiates the ultrasound, the
users can feel tactile sensation on their bare hands in free space with
no direct contact.

The current version of prototype consists of 324 ultrasound trans-
ducers. The resonant frequency is 40 kHz. The phase delays and
amplitudes of all the transducers are controlled individually to gen-
erate one focal point and move it three-dimensionally. The total output force within the focal region is 1.6 gf. The diameter of the focal point is 20 mm. The prototype produce sufficient vibrations
up to 1 kHz.

2.3 Hand Tracking

While camera-based and marker-less hand tracking systems are
demonstrated these days, we use Wiimote (Nintendo) which has
an infrared (IR) camera for simplicity. A retroreflective marker is
attached on the tip of user’s middle finger. IR LEDs illuminate the
marker and two Wiimotes sense the 3D position of the finger. Ow-
ing to this hand-tracking system, the users can handle the floating
virtual image with their hands.

3 Application

The developed system can render various virtual objects because
not only visual but also tactile sensation is refreshable based on
digital data. It is useful for video games, 3D CADs, and so on. Here
we show an example of demos. Fig. 1 shows a demo in which rain
drops fall from above. When the rain drop hits the user’s palm, he
feels tactile sensation created by the ultrasound. In another demo,
he sees and feels a small virtual creature running on his palm.

NICT Reveals Display Operated by Touching Floating Image

Apr 17, 2009 11:57

Yukiko Kanoh, Nikkei Electronics

The National Institute of Information and Communications Technology (NICT), an independent administrative institution in Japan, developed a display that can be operated by touching an image floating in the air.

For example, the "floating touch display" is expected to be used for medical purposes and for cooking because it can be operated while keeping the hand clean or operated with a dirty hand.
Optical devices developed by NICT are arrayed on an LCD display to show an image on the display as if it is floating in the air. The position of the fingertip touching the floating image is detected by an infrared touch panel with no glass.

The floating image is very solid. And it is possible to view an image that is staying motionless in the air even when the line of sight moves in any direction.

The optical device developed by NICT is an imaging optical device that uses a micromirror array to form a real image from a mirror image. This optical device enables to display a floating image by forming a real image as a concave mirror or convex lens does. However, different from them, it does not distort an image even when the image is formed from a 3D object; therefore, the position of the image does not move regardless of movement of a viewpoint.

There is a problem that the size of the optical device is too small, limiting the size of the floating image. But NICT plans to solve this issue by developing a new manufacturing technology. It aims to display a full-size image of a person in three years.