OK, maybe ‘official’ was a bit pretentious, but this is a very hot topic right now, let’s see if we can pool our collective knowledge on this subject in an easily findable unique thread.

AlexP started the ball rolling with his work with a single laser and a cylindrical lens (taken, I believe, from a Craftsman laser level). Straight from the horse’s mouth:

The lasers that I use are all custom made.

Hese are the specs:

- 850nm laser diode with 10mW (max power)
- Laser diode power supply circuit (photo-diode feedback LD current control)
- Focusable line with 120° spread using a special non-linear lens (even brightness)
- Variable voltage supply 3.5V-5V

I had a bunch of these modules prefabricated for me, and I have some extra.
If anyone of you is interested, you can have them for $95/each.

~Alex

Other threads have mentioned using IR lasers from either a CD-Rom drive or DVD burner drive (I think). I personally have not seen this done yet, but I’m very interested in doing so.

The laser beams must (?) be put through a dispersing lens, which may be as simple as putting a glass cylinder in from of the laser. Anyway, I think the main 2 topics of inquiry right now that I’ve seen from people are:

1. How can one pursue this technique cheaply? Do CD/DVD IR lasers provide enough coverage and power to give consistent results?
2. Where can one find the cylindrical lens? May already be an answer with the laser level idea, but if anyone has a better idea go for it.

You can use the stem of a good quality wineglass for a cylindrical lens.

Oh yeah, it may have been you that linked to the instructable with that idea…

http://www.instructables.com/id/3-D-Laser-Scanner/

This proves that you don’t really need to spend much money on the lens, just find a glass cylinder that is as uniform and clear as possible.

Also, the goggles. Remember the goggles…

I think an idea would also be to place mirrors all around the edges. Lasers are really powerful so this would make the beams bounce around the frame many many times. I’m just not sure wether it might be dangerous - light leakage is not cool when we are talking invisible lasers… However, it might enable us to only use 1 laser for an entire screen.

Hi all,
I’m also very interested in the laser version of the multitouch.
Standing to the informations that I found, CD burner lasers are preferable than DVD ones because CD lasers are infrared (around 780 nm) and DVD laser are visible red (around 650 nm).
Knowing this, I took apart an old CD burner that I had and shooted this short video:

The result is promising as the laser was visible just with the webcam, a Fire-I firewire cam with no IR-coated fish-eye lens with two layers of burned photo negatives on it. I could not see any light without the cam.

So, this may be a good direction.
Actually I’m trying to collect exact information on the laser diode (model, type, frequency, power, input power etc.).
Next steps may be to focus on how to power up the laser diode in a proper way and how to obtain a cylindrical lens.

I’m guessing if a plexiglas rod may work out for this job, probably there could be some DIY shop that sell them out.

P.S. how to embed the Youtube video in the post?

Good stuff. I’m curious to see now if that laser diode from your CD drive is powerful enough to get the job done, or if you’ll need several of them.

As far as a cylindrical lens goes, try borosilicate rods, they’re made for glassblowing, and come in 4-foot lengths for super cheap here: http://www.stateofartglass.com/store/clearrod.html.  Often places like this will also have shorter broken lengths that they’ll sell for even cheaper. Hope this helps!

btw, BlaXwan, did you get somewhere with the cd-laser ?!

Hi,
Pole suggested me the Thorlabs website to find lasers, he found this one which seems to be pretty good for this application:
http://www.thorlabs.com/thorProduct.cfm?partNumber=L850P010
Now we are trying to find the right lenses, then we will order everything!
So, as I think we’re going to find everything, I preferred not to destroy my (still working) cd recorder :o)

Does anyone have any sources of resonably priced 10mW IR ~850nm laser modules. It seems that the more powerfull 10mW come in diode form only. I’m not that familar with assembling lasers but can any powered housing be suitable for a diode as long as its the same size and meets the power requirements?

Hi,

I’m also very interested in the laser.
But I have some questions:
- Is “the laser 10mW IR ~850 nm” dangerous? What is its class (1,2,3a,3b,4..)
- How do you calculate the class of a laser?

If you must use eye protection is not ideal.

Kwarezim - 27 June 2008 07:31 AM

Hi,

I’m also very interested in the laser.
But I have some questions:
- Is “the laser 10mW IR ~850 nm” dangerous? What is its class (1,2,3a,3b,4..)
- How do you calculate the class of a laser?

If you must use eye protection is not ideal.

My CD burner has (lol i mean had) a class 1 laser in it..
IR are still dangerous for your eyes, just like normal lasers.. so please don’t look into them..

Laser classes: http://en.wikipedia.org/wiki/Laser_safety#Revised_system

Would there be an easy way to modify these: http://www.dealextreme.com/details.dx/sku.5928
to house these: http://www.thorlabs.com/thorProduct.cfm?partNumber=L850P010

That way we have our filter and an actual IR laser and not a Red visible-light laser?

I’m not all too familiar with electronics but it seems doable.  The whole deal would cost about $25 per laser which seems like a pretty good price point.

Any suggestions?

I’ll let you know when the bits arrive at my door.

I just bought two lasers today. I should be getting them next week. I’ll post my results when I get to test them.

Kwarezim - 27 June 2008 07:31 AM

Hi,

I’m also very interested in the laser.
But I have some questions:
- Is “the laser 10mW IR ~850 nm” dangerous? What is its class (1,2,3a,3b,4..)
- How do you calculate the class of a laser?

If you must use eye protection is not ideal.

Hey Kwarezim,
If you haven’t seen it take a look at the thread here about the laser safety.

~Alex