About the infra red laser :

After a quicksearch (instructable , youtube) it seems very doable removing the diode from a CDPlayer CD Player --- <2mW @ 780nm or buying one DL7140-201S/ 785 nm, 80 mW Sanyo Laser Diode / Each 42,80 €

An IR Laser is a very efficent way of making a bright IR light: Just diverge it with a lens. Conversly if used for target designation, just collimate it.
Lens A curved piece of optically transparent material which depending on its shape is used to either converge or diverge light.
from http://www.lasercommunity.com/military-scope-uses-infrared-laser-for-illumination-t15974.html
FRom http://www.lasercommunity.com/output-of-various-media-player-laser-diodes-t15725.html

IR laser viewed in infrared Have a look on this impressive IR light

No burning effect avoiding focus point as shown in:

and the question is : which lens should we use to diverge the light ?

actualy someone from this forum worked on the original photosynth (photo turism).

The 5 mW diode is like 35 bucks on that nvginc site

TouchWall consists of three infrared lasers that scan a surface.

so what i think is, instead of thinking over how to scatter IR light from an IR Laser diode ...... we can use 3 laser diodes to scan the whole screen .... just like the electrom beam in CRT and picture tubes .....

*EDIT*
doh! ..... i posted the above till the video was getting buffered ..... but wen i saw the video, then i knew tht these ppl r scattering the IR Laser light .....

Scattering the IR light in front of the screen is nothing new. It was on the Nuigroup wiki some time ago, it was called “grid setup” or something.
The main problem I see, is that you cannot make an even surface with this setup (like DI), because you need the lasers on top of the screen.
Plus, there is a company that makes something like this for high res lcd screens… smartscreen or something. They have the IR Light and the cameras on top of the surface,
but can only track two inputs/fingers at a time… there was a video from autodesk floating around two monthas ago, that probably used this screen..

But cool move microsoft, so now you can also build a wall… BUT WHERES THE BEEF
Honestly, still a pretty cool and cheap setup too… even with the 1024x768 resolution

tim

If you are talking about the “smart board” that I know it doesn’t support 2 touches at least in stuff that I have done with them in school. And you would definitely need to scatter the light or you would need like a million laser diodes because there wouldn’t be enough laser light over the screen for your fingers to disrupt otherwise.

I think they are using a small convex mirror over the laser and a plastic cap with holes trough it to scatter the light.

Hi Tim,

i didn’t find any of your “something reference”

wouldn’t it be a convex lens not a convex mirror?

My bad , i ment lens not mirror , the booze really got to me last night =))

Heh, I was just e-mailed a link to this. Came on to the boards to post and lo and behold, its not news I thought the idea of scattering IR light from 3 IR lasers was brilliant, so much simpler than using tons of IR LEDs. When someone brought up the idea of using CD-Rom lasers I remembered seeing them on one of my favorite electronic parts dealer websites...so here ya go:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G4119

I can’t wait to get started making one of these surfaces myself, its hard getting the money needed for projectors / other parts :S

Edit: Hm, I’ve just thought of something. Another advantage of using IR lasers in this arrangement is that you don’t have to worry about all that compliant surface stuff, which to me seems like a HUGE hassle. Am I wrong? I hope someone is able to experiment with this.

I’ve solved the puzzle.They use a diffraction grading above the laser.I found a place online that sells the material , to bad they don’t ship to Romania.

hey Vlado , sounds interesting ,let us know the missing pieces !
“diffraction grading above the laser.I found a place online that sells the material “

send the link , if required ,possible,affordable , i will send it to U !

This guy explains it better than I could ever do it

You can buy diffraction grating from this site http://rainbowsymphony.com/ in the form of glasses (with little sheets of d g over them) or a bigger sheet and you cut it to custom size.
With this diffraction gratings over the lasers , we should have MS’s TouchWall.

I think we could build a system similar to the Wiimote Whiteboard , with 2 cameras from 2 different angles and based on OpenCV or something.
By doing this we would have true multitouch over any surface with the cost of 3 portable IR lasers.

Huge Vlado ,well done ,
here another explanation more precise !
i will definitly try this ,
the idea with the three laser and diffraction grating is to make a curtain of lights , a vertical array ,a BEAM ARRAY aka. LIGHT CURTAIN as shown here

(is that this last ref you wanted to mention Tim Roth ?)

So only one camera is required