Infrared Light (Newbie Question)

Hi

I'm looking into a potential for a high school engineering project. It's pretty easy and straightforward, but I need some sort of laser that emits infrared light, that can be picked up by an infrared camera.

I was wondering what lasers emit enough infrared light to be picked up by an infrared camera, and are still cheap (high school student budget).

Thanks.

Infrared lasers are the only ones that emit infrared light.  *Some* cheap green lasers may leak some, but it won't be collimated/focused, and there won't be much of it.  In fact, if it is a quality laser, I daresay it won't emit any IR at all.  So I would probably recommend that if you don't want to build one yourself, just hope on over to the Buy/Sell/Trade section, post a WTB: IR laser topic.

If you can solder, you're perfectly capable of making one yourself.  How much power do you need?  I'm not sure of the required thresholds, are you looking to be able to see the beam in the IR camera or just see the dot in the IR camera? If it's less than 200mW, you can order a diode Here----> http://stonetek.org/shop/ under "Diodes".  So if you just need 5 or 10 mW of 808nm IR, that diode is less than $10, and you can put it in a pointer for another $5 or $10 for the cost of a proper driver plus the cost of whatever host you want to use, and you can set it to give you any power that you want up to the maximum of 200mW. Also, that diode is 808nm, so at high powers, the dot may actually be partially visible to your eyes. I'm really not sure about how an IR camera would handle the 808 specifically, but a lot of normal digital cameras can actually see it better than your eyes can.

Also, if you're going high in power, remember SAFETY.  I'm sure you've looked at the dangers or IR light, but just remember with high-power collimated light, you're entering a whole different world than just IR LEDs.  200mW of IR, even from just reflections, can damage your eye faster than you can blink, and you'll never know it until it's already too late and your retina is scorched.  I highly recommend safety goggles and other safety precautions (especially if taking it to your high school) if you've never used such things before.  808nm may be barely visible to you as a deep red, but it's visibility doesn't match its true potential for damage.

Thanks for the advice.

So, 10$ for a diode and $10 at the most for other parts? Sounds cheap enough.

I only want the camera to be able to see the dot, not the beam. I'm not sure if you've seen the experiments that were done with the Nintendo Wii Remote (which has an infrared camera on the end) but my plan is to have the camera pick up the dot from the laser on the wall (or projector screen, wherever it's being shined). I don't want it to see the beam.

Are there any detailed instructions on making a "DIY" laser that would help me buy the right things and put them all together?

Also, as far as safety goes, will it be dangerous to be shining it on the wall of a classroom for a demonstration?

Most of the red DIY tutorials can probably be used for an IR laser,

Yes it is safe to look at the dot from about 10mW of IR, but I wouldnt recommend looking at the a 200mW IR dot without safety glasses.

Also if it's only 10mW or so you wont see the beam with a camera, unless you use smoke.

-Ada,

Yep, $10 for the diode, $10 for RadioShack parts, and whatever host you want to put it in (black project box is nice and easy, run it off of a 9V battery). An LM317T driver is nice/easy and you can get all the parts at RadioShack, look for "DDL driver" on this forum. Someone else could possibly give a diagram, I don't have one handy, but it's really simple. With a potentiometer, you can look at the dot with the IR camera, and adjust the power to be whatever the minimum it is that you need it to be, but adjust the potentiometer with the laser turned off and check the current before testing the laser each time.

I don't know what current to drive the laser diode at, someone else (Stonetek says the Hemlock Mike is working on a graph, possibly) could also give you a current input vs. output power for the diode. For just the dot, I don't guess you'd need over 5mW, so I'd stick to low numbers to avoid any possible problems with safety or anything. Someone else should chime in here as well, but diffuse reflections less than 5mW I don't *think* would pose much of a problem. BUT, what saves us with visible lasers less than 5mW is that our blink reflex is fast enough to prevent real damage. With an IR laser, you won't have the same blink reflex to protect you. You still need to be very careful with it.

Also, you'll need a housing for the diode. The Aixiz housing from Stonetek is a good place to go ahead and get that too, and you might be able to get Greg to pre-install the diode in the housing for you for a few extra bucks.

I have an LM317 BR driver, its much the same except for the resistor and the cap.



-Adam