How To Turn a Mini Maglite Into a Laser

Lucas123 writes "Using the laser from a DVD burner, this instructional video shows you how to create a hand-held laser that is powerful enough to light a match and pop a balloon. There's some soldering involved and the Maglite's bulb housing needs to be drilled out to fit the new laser diode, but with some basic skill, most people could do this. Just plain cool." Update: 07/09 12:23 GMT by KD : Warning, the device that results from following these instructions will blind you if you look into it.

This is cool, but can it...

[Seismologist]

actually ignite a match like that? I didn't know that 2 AA batteries could put out that much power in a laser beam... this is clearly a lot more powerful than your standard run-of-the-mill laser pointer used in presentations. I'm so tempted on doing this.

This makes me sad.

[mdenham]

DVD players use a red laser; presumably Blu-Ray players use a blue laser (though why you're cannibalizing the operative piece of a $1k+ piece of... oh, wait, maybe you already converted your PS3 into a grill)... but there isn't anything that uses a green laser that's readily obtainable, is there?

Re:Great...

[Deliveranc3]

You know they're gonna solve that before we have kids.

Tiny Violin: Poor kids never know the simple pleasure of the laser :(

Re:Sure

[dido]

So you could do some real interesting things with a Blu-ray diode then...

2 AA batteries ?

[CharmElCheikh]

How long will 2 AA batteries last shooting so much power ?

Re:Shark

[Xemu]

Mounting the laser could be a slight problem if the shark is conscious

Just turn the shark upside down before mounting, that makes it go into tonic immobility for about 20 minutes.

Re:Laser Housing

[Slugster]

Re: Is the metal housing really necessary? ....Yes, for the most part.

I tried this some time back, and it didn't quite work, but I'll relate what I know anyway:

1. There's TWO laser diodes in a DVD burner--remove them both out carefully, preserving as much of the leads already-soldered-on as you can! The leads of the laser diodes are very short (maybe 2mm) and only about a half-millimeter apart, it's damn tough to get the longer leads soldered back on if you cut them off, and there's no need to cut them off and then attempt to solder them back on anyway.

2. Inside the DVD burner you will find TWO laser diodes, with mirrors that feed them both into the same beam. Each will be glued inside its own heatsink, a piece of metal that may be a very odd shape, and then these are attached to a bigger copper plate. To tell them apart, just test them--try applying 1.5V power to both diodes one at a time, the CD one is IR and won't appear to do anything. The DVD one will light up visible red. (if all the lenses are removed from them at this point, you cannot burn your eyes out, that's in the next step...)

3. The bare laser diodes don't put out a laser "beam", they just create a pinpoint light (that's safe to look at!). To get the beam, you must mount a fisheye lens with its concave side set very close to the diode, almost touching it.

4. The laser housing is a metal tube with a fisheye lense set in it. The laser diode will get warm with 1.5V on it, and will get too hot to hold in ~30 seconds with 3V on it. The laser housing serves partly as a heatsink, and also as a way to hold the lens without melting (the DVD-drive optics will have a fisheye lense, but those optics are usually set into little plastic frames, and they may melt in this use).

....Mine didn't work because I could not find a way to get the laser diode out of the original steel heatsink it came in. It was glued inside a hole about 6mm deep in a odd-shaped steel heatsink. You could maybe grind the heatsink away a bit at a time with a Dremel & cutoff wheel, but laser diodes are sensitive to heat, so you cant let the laser get too hot. I tried using mine still in its heatsink with other optics (telescope objectives and whatnot), and with those set in front of it, it would melt a garbage bag a little but wouldn't do much else.

IF you manage to get one out and do this, don't run it for more than ~20 seconds at a time without letting it cool down for a minute or so. The laser diode will work with 3V batteries hooked straight to it, but you're definitely not going to get that 100,000 hour lifetime. You'd be lucky to get 1000 hours. The DVD laser output power is typically around 210mW, and more than 150mW is enough to burn stuff (the CD laser won't burn stuff because it's only around 40-50mW max).
~

Re:Good plan

[Opportunist]

I'll call it natural selection and applied darwinism.

Re:Dangerous

[Anonymous Coward]

Even with a safety warning, where I come from (England), the local little horrors already often try and blind bus drivers with laser pointers.

If they get hold of one of these, I wouldn't like to be a bus driver. It's silly to talk about responsibility. These kids have none. And if they succeeded - there would be virtually no consequences to them - a telling off from the police maybe - while the bus driver is condemned to a life of blindness.

I'm not saying the solution is to ban this information. You can't. We are entering a pretty hellish world in some ways.

Re:Dangerous

[Anonymous Coward]

I've been reading Slashdot for 8 years, and this is the scariest comment I've ever read. Like, Horror Film scary. Really really scary. I'm glad things turned out okay. You should write a film.

Proper protection?

[z80kid]

We've all read the 92 posts saying how dangerous this puppy is. How about something more informative?

Anyone know an inexpensive source for protective gear (ie goggles) for those amateurs who will insist on playing with something like this, but would like to do so responsibly?

(And thanks to dhalgren [slashdot.org] for the very helpful Safety FAQ [laserfaq.org].)

Re:Dangerous

[Anonymous Coward]

I'm increasingly of the opinion that the only proper way to pounish somone who intentionally wounds/maims someone is to do the same thing to them. Only withplenty of warning so they have time to get really fucking scared. No other punishment really means anything in the end.

You blind someone intentionally - say goodbye to YOUR sight.

Re:Laser diode may not last too long run like this

[Anonymous Coward]

In general, yes, in this particular case - no. Diodes meant for DVD burners typically don't have a feedback diode (These things are supposed to be run closed-loop with the read sensor). Also, these things are actually rated for even higher peak powers - a 130mW continuous laser is spec'd to run at 300mW for pulses, and will run even higher if you don't mind killing it faster. The short of it is that these things seem to be "relatively" robust to catastrophic optical damage (i.e. smoked mirror), but do need some serious heatsinking.

Ref: HL6545MG Hitachi laser diode
http://www.photonic-products.com/products/laserdio des_visible/hitachi_visible_ds/hl6545mg.pdf [photonic-products.com]

Re:Laser Safety, Standard Operating Procedures, Ge

[alienw]

The optical DRIVE is class I, because it's enclosed by a metal box and has interlocks, thus posing no danger if operated normally. The diode inside can be class II, III, IV, or whatever. Every DVD drive would have similar power output, since that's what it takes to burn DVDs.

Re:Dangerous

[rpbird]

This is no joke. A certain percentage of ADULTS will look into it. My old Astronomy professor used to invite his students to solar observations in the little observatory on top of the science building. He had to stop when, time after time, after numerous warnings not to cross or even approach the focal point of the projection (a variation of Galileo's projection of sunspots), one or two would always try. He'd pull them back. One time he didn't get there fast enough and a TWENTY-something student stuck his arm in it. Fortunately, it was cold outside, the guy was wearing a plastic windbreaker. The sleeve of the windbreaker went into the focal point. Pow! The guy pulled his arm back before he was burned. My professor gave up. He'd invite people he could trust to observe, but it was no longer open to the general student population or the public. We all think it's fun to make dangerous things. I've done it, and if you're honest, you've done it. We were the lucky ones, we didn't get blown up or scarred for life. I met one of the unlucky ones, who blew off his hand and put out an eye trying to make homemade fireworks. Always warn them! A few won't listen, but many others will. With this laser project, someone should have emulated the Mythbusters: "Don't try this at home....ever!"