LLP Multitouch Zero Force Setup Take #2

Every since posting the results of my previous setup, I worked on improving some aspects of this setup.
During this time I decided to make a vertical version and at the same time test my new 850nm 10mW laser that this time featured more advanced version of the line generating lens. This reflected in fully uniform brightness across the line width and wider coverage angle.
Because of all of this, I found that using only one laser was sufficient enough for simple multitouch operation.

See it for yourself…

Here are the results:

In action:

Sun light front view:

Sun light rear view:

Enjoy!

~Alex

*jaw drops*… that is just amazing stuff man… truly stunned

LLP is pure ... elegance

*WOW*.... so this produces blobs then, eh? i guess i kept thinking with the laser light stuff that it would need to find which lines are being intersected by fingers or something, but i guess that just results in an IR illuminated blob? (edit, sorry… just read previous thread… way too cool, guy, good job)

nuiman - 06 June 2008 07:09 AM

*jaw drops*… that is just amazing stuff man… truly stunned

is that using FTIR or DI?

Not sure it has a name yet , as the IR is being projected onto (just above) the front of the screen.

Alex: Looks great and very responsive.
Any chance of providing some details on the laser and lense, as it looks like you have has a little upgrade from the laser level you took apart before
I did a search but there are lots of options, so not really sure whats the best one to buy.

Great job , this looks alot better than FTIR.It looks faster and there’s no need for pressure.

hrmmm ... Laser Illumination (LI) ... diffused laser (DF) ... although, sort of diffused at touch, not diffused like DI hehe ... i dunno....

APTASONG : AlexP Technique As Seen On Nui Group

Wow it loooks amazings.... great work.

Taha

This is taking it to the next step.  From “hey that kinda works” to corporate office ready!  Thanks for the great work. 

I’m jumping to build my own laser model.  I’ll be on vacation all next week but when I get back I’m on the bandwagon for sure.

Nice post again AlexP! You’re doing great work =)

Would this still have the issue of blocking blobs if fingers are next to eachother since the fingers are only being illuminated from one angle? The other downside that i’d miss is the ability to interpret finger pressure since that can be really important sometimes. Do you think this technique could overcome these obstacles? Like the other techniques, it seems there are definite limitations to this design still.

I think if we could modify the design to incorporate the benefits of the other techniques this would be great. FTIR’s pressure sensitivity, DI’s ability to track fiducials and laser’s ability to send bright output at small wavelengths would be great.

That’s awesome.. What laser are you using with that set up?

cerupcat - 06 June 2008 11:58 AM

Nice post again AlexP! You’re doing great work =)

Would this still have the issue of blocking blobs if fingers are next to eachother since the fingers are only being illuminated from one angle? The other downside that i’d miss is the ability to interpret finger pressure since that can be really important sometimes. Do you think this technique could overcome these obstacles? Like the other techniques, it seems there are definite limitations to this design still.

I think if we could modify the design to incorporate the benefits of the other techniques this would be great. FTIR’s pressure sensitivity, DI’s ability to track fiducials and laser’s ability to send bright output at small wavelengths would be great.

The blocking issue could be fixed by using more than one laser light source.
As is it the case with FTIR, from my experience, the finger pressure is also detectable by this design.
Here is how it works:

Since the laser plane of light is about 1mm thick and it is positioned right above the surface of the acrylic/glass, when the finger just barely touches it, it will hit just the tip of the finger which will register as a small IR light blob.

Here is the low finger pressure illustation (borrowed and modified J. Han’s diagram here):

Now, when you apply more pressure the larger part of the finger will be illuminated by the laser light plane, which will result in larger blobs.

Here is the high finger pressure illustation (borrowed and modified J. Han’s diagram here):

I think that fiducial tracking is also possible with this method.
One way that this could be done is by using some kind of selectively difused and transparent material that will light up when placed in the laser light plane (create kind of FTIR effect within the material). So using this method the fiducials will be the inverse of the ones that are comonly used.

Hope this will clarify some of the questions…

Alex

@ Nick
@ th0m
@ gally

I would call it: Multitouch using Laser Light Plane illumination, or LLP method.

Alex

Sounds good! I am still wondering what kind of laser you are using and if it would be possible to get one from the same place you did?
Great work, and I like the name.

Thanks for the diagrams. One of the benefits of FTIR though is that for pressure, not only does the area of the touch change, but also the intensity of the light can change. Measuring area as pressure isn’t always really accurate since some people use the tip of their fingers while others use the pad of their fingers (while the pressure remains the same). As for the fiducials, that an interesting concept. It would definitely be more complex than just printing a fiducial on paper. It be interesting to see that suggested technique prototyped.

Are there any issues in that the actual touched area isn’t lit up (only the surrounding of the touched area)?

I hope I’m not sounding negative towards method. I really think it’s great. I’m just trying to spark some questions/thoughts to help improve it and bring the benefits of other techniques to this one.

WOW !!! BRAVO !!