Author Topic: IR Laser?  (Read 43363 times)

Offline gabort

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on: January 10, 2008, 08:01:38 PM
First, before even considering this I would like to know, what is the safety threshold?

Just because IR is invisible, it does not mean that it can not cause blindness. There are some very powerful diodes out there, and the fact that you can't see the light makes it all the more dangerous.

I can live with power that will damage your eye if you deliberately look into it for an extended time (after all, poking the pen into your eye will have a similar effect, and is just as stupid), but I would still insist on using it only in conjunction with a red laser alligned in parallel, so that the user is at least aware of the imminent danger. (could be usefull too...). If the laser is too powerful, even scattered light bouncing off the wall could produce permanent eye damage.

So the question is: What power laser diode is safe for such use? I've seen 850nm lasers from 5mW, to 200mW and above. Motto: If you go blind, you will not need a whiteboard...

If we know that, we could check and see if the Wiimote "sees the point"...



Offline Der Wichtel

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Reply #1 on: January 11, 2008, 07:39:28 AM
I know that green laserpointers are producing infrared light.
The expensive ones have filters but the cheap ones do not have good filters. Therfor you can try a cheap green laser pointer. The poweroutput does not have to be very high.



Offline adrintoul

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Reply #2 on: January 11, 2008, 02:09:35 PM
I know that green laserpointers are producing infrared light.
The expensive ones have filters but the cheap ones do not have good filters. Therfor you can try a cheap green laser pointer. The poweroutput does not have to be very high.

I have this green laser pointer http://www.thinkgeek.com/gadgets/lights/5a47/, but it does not register with the Wiimote.  As far as infrared lasers go, all the ones I could find were powerful enough to be dangerous (popping balloons, burning paper, etc).



Offline gabort

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Reply #3 on: January 12, 2008, 12:06:49 PM
I was looking at components, and they sell some that only do 5mA. I'll ask around first though, because I know they could be dangerous. A 100mA led is ok, because it radiates it's power at 30 degrees, so the density of the light is much lower. Something that concentrates nearly all its power in a tiny dot provides light that is far more dense, even if its overall power is less than that of the led.

I found things like this:http://www.worldstartech.com/products-ldm_uhl_series

But it's hard to miss this, at the end of the specification sheets...



Offline Thinksamuel

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Reply #4 on: January 12, 2008, 08:11:39 PM
So it is possible to use a laser pointer instead of a constructed IRpen? If that would be the case, i would be really happy, ok you et red light but that's not a big deal for me



Offline atomriot

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Reply #5 on: January 12, 2008, 08:16:45 PM
yes but constructing the pen is half the fun.

hmm... but changing and compiling the code is half the fun to...

ok so maybe its just a third the fun so you can actually have fun with the app.

Details, details. Things to do. Things to get done. Don't bother me with details, just tell me when they're done.
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James Lionel Price



Offline troy59

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Reply #6 on: January 16, 2008, 02:16:32 PM
lol, i made a ir pen, but i put a red laser pointer on the side of it and i stood like three feet away and used the laser dot as a pointer to see were my mouse was going, it worked great



Offline gabort

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Reply #7 on: January 17, 2008, 06:38:19 AM
Let me get this very straight: You used an IR laser?
OR was it a normal LED based pen that worked 3 feet from the screen?

Pls. go into a little more detail. thx.



Offline troy59

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Reply #8 on: January 17, 2008, 09:50:09 AM
basically, i built an ir pen, a plain normal ir pen, i was kinda going for a futuristic effect, so i decided to stand like 2-3 feet away and try it, but the wii mote couldn't see it(the wii mote was behind me) so i put it in front of me below the tv. Then it worked but i didn't know how far or were the mouse would be going so i added a normal red laser pointer(one i bought for like 4 dollars) and attached that too it. It made a dot on the screen so i used that to help me callibrate the ir pen. it works great, heres a diagram i made on painthope this helped,



Offline gabort

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Reply #9 on: January 17, 2008, 01:42:44 PM
No offense, but I have my doubt on the accuracy of that setup. If you tilt the pen, the laser will show at a different spot on screen, yet there will be no precievable change from the Wiimote's point of view.

Also, to my own question: Here is a classification of what lasers may yet be safe.
http://ptcl.chem.ox.ac.uk/MSDS/laser_classification.html

I also found a chart on another site, and inserted a red line into the approximate wavelength the Wiimote senses. It does not look very good, we really need to be careful with an IR laser.


Source: http://www.asu.edu/radiationsafety/laser

For a first experiment, I want to try a real low power device.
« Last Edit: January 17, 2008, 01:54:57 PM by gabort »



Offline troy59

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Reply #10 on: January 17, 2008, 04:37:50 PM
no, it has nothing to do with the laser, the laser is there just to show were my pen is going, nothing else, it would be way too hard to make it so the wii mote detects it.



Offline gabort

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Reply #11 on: January 23, 2008, 11:38:18 AM
Today I orderd an IR laser pointer from Vienna. It is supposed to be eye safe, and cost me about 40 EUR.

I can't wait to try it out. I'll let you know, if it works, when I get it.

RLT-302UC, 980 nm, < 40 mW, 3 x LR44, eye safe operation



Offline troy59

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Reply #12 on: January 23, 2008, 03:13:40 PM
nice, good luck



Offline gabort

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Reply #13 on: February 03, 2008, 05:01:22 PM
Well, it does not seem that IR lasers can be used effectively.

The model I was hoping to get was no longer in stock, but a laser module with essentially the same specs let me carry out the experiment, none the less.



Here's how it ended up looking, when I assembled it into an old pen:



It has a nice focusable end to it, so that's not why it essentially failed.



The Wiimote is completely oblivious to the beam. The only time it takes notice, is if you shine it right into the camera... I tried all sorts of surfaces - shiny, dark, smooth, rough - NOTHING.

I suspect that the beam was simply not strong enough (the wavelength was spot on).

I used a 2mW laser. Now a 20mA (amp, not watt) led in my first led-based pen that was too weak for my taste is essentially a 3mW output at 1.5V. So 2mW might not be enough. A 100mA led that works fine is 15mW output at 1.5V. So that might explain it... on the other hand, I was just not willing to risk damaging my eyesight with something more powerful.

Cost is also a factor. If you look at some of the more powerful laser modules, 20mW and above, its well over 150EUR, which is out of range for such low budget simple solutions. Also, the beam might be powerful enough to blind you, or someone else.

So, while this is not the answer I was hoping for, I think we can declare IR laser based solutions with the Wiimote a flunk.



Offline Der Wichtel

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Reply #14 on: February 03, 2008, 05:19:50 PM
What is its wavelength?

The wiimote doesn't see my laser either
http://www.wiimoteproject.com/wiimote-whiteboard/test-with-irlaser-t287.0.html