Holography is considered as one of the most remarkable discoveries in modern times. Nevertheless for its first decades it seems to be getting forgotten.

Originally stepped up back at the end of the 1940s to improve electron microscopy, it can not fulfill this function and the wish of its discoverer hungarian-british physicist Dennis Gábor. Due to sources of pure coherent light, which are indispensable for optical holography, being not yet available, not even Gábor himself can locate a field of application for this phenomenon. He can neither recognize at that point of time the meaning and the potential of his discovery and with it the influence this new medium would have on our daily lives one day. Nor can he imagine the plenty of phantasms emerging from this phenomenen. Phantasms, which seem to be mostly one step ahead of applied holography.

With the discovery of laser light at the beginning of the 1960s, for the first time ever it becomes possible to record and reconstruct a real three-dimensional image of an object. What once simply starts as a little rainbow coloured picture of a toy train, today finds its applications in a vast variety of different optical and acoustical fields.

It is as remarkable as the phenomenon of holography itself, that it could never prevail as a popular medium like movie, TV, radio, the internet, print media, etc. Especially when keeping in mind all the phantasmatic stories which emerge from this medium. A lot of dreams, hopes and promises that holography never made by itself, but some of them is trying to keep.

blog.holographie.eu accompanies my scientific work on holography, which would like to give holography an attention, that elsewhere is mostly refused to it. It is of course initially interested in based techniques and technologies of holography and how it works. Moreover it is also interested in these upcoming phantasms and their stories arising from possible abilities of holography. Especially against the backdrop of holography seems to be reaching a point, where its possibilities and abilities catch phantasms.

This blog would like to serve as a sketch book for unprotected ideas, of which some maybe become expanded, while others are not haunted any further, but wants to be told and should not be unmentioned forgotten.


please visit also www.holographie.eu

2010-03-01

Airborne ultrasound tactile display

About one year prior Hiroyuki Shinoda adds the Wiimote hand tracking system to make up touchable holography preliminary, he presents an airborne ultrasound tactile display at SIGGRAPH 2008 (International Conference and Exhibition on Computer Graphics and Interactice Techniques), which ought to be introduced a little more detailed in this entry, as the second method of touchable holography - excluding the projection of a 3D floating image.

Airborne ultrasound tactile display radiates airborne ultrasound and produces high-fidelity pressure fields onto a user's hand. This method is based on a nonlinear phenomenon of ultrasound. Unlike air-jet, generated fields of static pressure can be localized and do not cause unnecessary vibrations. When this propagation of ultrasound is interrupted by an object, a pressure field is exerted onto its surface. This pressure is called acoustic radiation pressure. The spatial distribution of ultrasound is controlled by multiple ultrasound transducers, based on wave field synthesis techniques. Using these techniques, various patterns of pressure field can be produced in 3D free space. Airborne ultrasound can be applied directly onto the skin without the risk of penetration. Tactile feedback is provided to the users' hand without requiring gloves or any other mechanical attachments.


Airborne ultrasound tactile display


Tactile feedback is superimposed over 3D graphics projection. The generated pressure field corresponds with the 3D virtual image. The sensation of touch would be broken, for the synchronization between pressure field and image doesn't work.

The goal of this technique is to considerably improve the usability of systems, which enables users to manipulate 3D graphic objects with their hands. It can find application e. g. in video games or 3D modeling software. "It might also be useful to manipulate small particles or probingg the surface of an object to measure the viscoelastic properties of the object from a distant point."


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