# IR Laser Diodes - are they good for anything?



## IgorT (Oct 24, 2007)

Hi guys!

I just wanted to ask about the IR LDs from the DVD burners..

Supposedly they have an even greater output power than the red LD.

But when i connect it and try to observe the result on a CCD camera (i don't look into it, i'm not stupid) it barely lights up, approximately as much, or even less, than an IR LED would...

Anyone know anything about this?

Is it possible to make it into a burning invisible laser?


BTW: I know IR LDs are more dangerous than the red ones, since there's no blinking reflex and they can damage your eyes without you even noticing, but i just want to know..


Thanks!


Igor


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## Greg G (Oct 25, 2007)

How many watts is one of these supposed to be?


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## IgorT (Oct 25, 2007)

Greg G said:


> How many watts is one of these supposed to be?


 
From the specs i've seen, when the red LD in the drive was 225mW, the IR LD was 250mW or even 280mW... (for 52x CD-R writing)

That's why i was thinking it should definately light up more on a CCD then an IR LED would...

But i have found a slowly trickling, but potentially unlimited supply, so i can do a lot of testing...


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## paulr (Oct 25, 2007)

For cripes sake put that thing back in the DVD burner. They are good for burning DVD's. Isn't that enough? Outside in the wild, sooner or later someone is going to look into it asking "is this thing on?". Oops.


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## RDZombie (Oct 25, 2007)

paulr said:


> For cripes sake put that thing back in the DVD burner. They are good for burning DVD's. Isn't that enough? Outside in the wild, sooner or later someone is going to look into it asking "is this thing on?". Oops.



HAHAHA I was thinking exactly that. Someone’s going to screw up big time and look into it. 

Also IgorT, do you know what wavelength the LD is? CCDs wok better with visible and near infrared. Deeper IR wavelengths don’t show up too well with standard CCDs


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## IgorT (Oct 25, 2007)

paulr said:


> For cripes sake put that thing back in the DVD burner. They are good for burning DVD's. Isn't that enough? Outside in the wild, sooner or later someone is going to look into it asking "is this thing on?". Oops.


 
Actually it's only good for burning CDs, but i guess that's what you meant..

Otherwise i know exactly what the dangers are. I'm not stupid.. That's why i was observing it through the CCD..


BTW: The wavelength is 725nm or something like that. I'm not sure, i'll check in the evening.


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## IgorT (Oct 27, 2007)

I noticed something interesting yesturday, while trying to see if the red LDs from combo drives could be used as slightly stronger laser pointers..

The LDs were very easy to get out, but i didn't know which one is red and which is the IR one..

The first one i grabbed hardly put out any red light whatsoever.. I was worried this could be the IR one, since those sometimes also put some red light out.

Then i tried the other one and observed the results indirectly (through the CCD) just in case. This one is MUCH stronger. It completely blided the camera even when it was pointed away from it..

So either the IR LDs from combo drives are stronger (higher speed of writing?) or i damaged the DVD writer IR LD... The difference is like 10x more IR light...


I immediatelly put it in a safe place and marked it for what it is.. Dangerous..


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## steve2004 (Oct 30, 2007)

IgorT said:


> Hi guys!
> 
> I just wanted to ask about the IR LDs from the DVD burners..
> 
> ...


 
another use for the IR pointer:





Good for "night Paintball" wargame !!


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## IgorT (Oct 31, 2007)

steve2004 said:


> another use for the IR pointer:
> 
> 
> 
> ...


 
Hehe, good one.. I would expect the beam to be very visible with night vision goggles..

So are they actually used in this way?


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## Heruursciences (Nov 1, 2007)

the ccd camera has a filter that blocks near ir, use a lens and focus the output on electrical tape.


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## IgorT (Nov 1, 2007)

Heruursciences said:


> the ccd camera has a filter that blocks near ir, use a lens and focus the output on electrical tape.


 
Actually i tried an IR LD from a CD-RW combo drive (read DVD but no write) and that one was much stronger.. It actually completely blinded the camera even when directed away from it.. It's possible that i damaged or destroyed the IR LD from the DVD burner, or that it's just less powerfull (lower CD writing speed)...


BTW: How do you focus an invisible beam, without using a CCD camera?


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## steve2004 (Nov 6, 2007)

IgorT said:


> Hehe, good one.. I would expect the beam to be very visible with night vision goggles..
> 
> So are they actually used in this way?


 
saw this:










would be cool to try..


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## IgorT (Nov 6, 2007)

steve2004 said:


> saw this:would be cool to try..


 
Since the night vision goggles use IR light for illumination, to avoid detection, it would make sense to use IR lasers at the same time..

Good pics BTW..


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## steve2004 (Nov 7, 2007)

IgorT said:


> Since the night vision goggles use IR light for illumination, to avoid detection, it would make sense to use IR lasers at the same time..
> 
> Good pics BTW..


 
check this video from Youtube:

from the US Army:

http://www.youtube.com/watch?v=D7YzM1tnMhE
http://www.youtube.com/watch?v=AoblNytUocA

this is cool... taking down the ennemy in the dark!


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## Phenol (Dec 6, 2007)

when comparing dvd and cd writing speeds, take account of the actual speed. 1x cd writing speed is approx 9 times lower than 1x dvd speed. do the math for a 52x /or 48x cd wr speed in most dvd burners/ compared to a 20x dvd speed. if we suppose that it takes similar amount of power to burn cd and dvd media, it turns out that dvd burner LDs are actually more powerful than cd burner LDs. I saw a 48x CD LD die in my hands while lasing at only 150mA. It was pressed in a brass module and practically remained cold. Its bigger dvd neighbour safely copes with current above 250mA. Also, comparing their chip sizes, dvd LDs are bigger.


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## Athoul (Dec 8, 2007)

CD-Writers contain laser diodes of ~40-60mW @780nm. Those in DVD-writers may be slightly more.


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