Fun With Lasers
Howto: Make a DVD Burner into a High-Powered Laser
The laser pictured above has a peak output measured at 225 mW (average output 200 mW). It's a visible red at about 650nm. It can light matches, pop balloons, cut electrical tape, and so forth. It can do pretty much anything a Pulsar 150 from Wicked Lasers can do, because it's basically the same thing. The only differences? This laser was home-made, and cost about 1/3 the price.
So, how did I do it? Some luck, some deductive reasoning, and some electronics experience all come into play. This page is a brief guide.
Step By Step
Step 1: Get a Laser Diode
DVD-RW drives are quite common today. The faster ones require a high-powered laser in order to generate enough power, fast enough, to do the job. I suppose it's the luck of the draw what exact diode they use, how it's powered, etc etc. This is where I got lucky.
This is the DVD drive I bought for $39.99 (Canadian), for the express purpose of tearing it apart for a laser diode:
Once I had the DVD drive, it took me less than 15 minutes to completely strip it and extract the optical works. There were two diodes, lots of little mirrors and things, and some circuitry. It took another few minutes to extract the two diodes with their heat sinks. The rest of the optical bits and pieces were saved, as was the motor that opened and closed the drawer - it can be used, with a mirror, to do effects. Everything else was junked.
Once you have the diode out, you need to figure out how to make it go, if it's visible or not, and if it's got enough power to make it worth your while.
The laser diodes I'm familiar with look like this:
They may not look exactly like that, though. Here's the actual diode and heat sink I took from the DVD drive:
Knowing that most laser pointers ran on 3v (two AAA batteries) I got a 3vdc supply and - aiming the diode emitter window away from me - I hooked (-) to the heat sink and touched (+) to one of the leads.
Presto! A huge flood of monochromatic red light all over my desk. So, I had a visible red laser diode!
How powerful was it? The best I could do was hold it a mm or two
from some thin black plastic and fire it up. It melted through the
plastic in a few seconds. Yep, it was strong!
In order to use the diode though, I had to get the laser diode out of its wierdly shaped heatsink. It was soldered in, and I know heat can be lethal to laser diodes, so it was a trick getting it out. I used solderwick to extract the solder, set my iron on fairly hot (short uses at high temp is better than long uses at medium temp), and managed to get it out without hurting it. Needle files were then used to clean off the rest of the solder, rather than risk more heat with the iron.
If you're lucky, you might even get a laser diode that is conveniently identified like this:
This turned out to take me a long time. I bought a cheap red pointer with plans to tear it apart and use its lens etc but it was junk. After lots of internet searching and reading, I found what I wanted. A metal 'heat sink' tube that held the 5.6.mm diode, and was threaded to accept a collimating lens. The only problem was it was a bit expensive - about $20, plus shipping.
Then, I received a laser module I'd ordered from AixiZ Lasers.
It looked like what I was looking for... I took it apart and confirmed
it! Not only was it the heat sink mount, but included the lens and an
extra tube at the back to house a driver and facilitate mounting in an
I immediately ordered another module from them: 10mW, 650nm. This module was only $12, plus $5 shipping. So for $17.00 (US) I had a complete mount and matching collimating lens!
The 10mW 650nm laser diode unfortunately did not survive the procedure of extracting it from the heatsink. The diode was press-fitted into the heatsink using friction to hold it still. Extraction involved use of a hammer directed towards the front-end of the diode to force it out the back of the heatsink. Nuff said.
With the laser diode, mounting hardware, and collimating lens, all
that remained was to do the electronics. I already knew, from looking
at the guts of a Pulsar, that you could run a red diode without any
driver at all - just wire it straight to the batteries. That made it a
So I opted for two AA NiMH batteries, a three position slide switch, a pushbutton, and a LED:
Pretty simple, the slide switch is 'off', 'momentary', and 'on'. When it's 'on' the laser is on full time, and the pushbutton does nothing. When the slide switch is 'momentary' the laser is off, until the pushbutton is depressed. The LED is wired with a 1k-ohm resistor, in parallel with the laser diode. The LED comes on whenever there is power going to the diode.
For diodes rated at 3 volts, running them off two NiMH batteries is really under-powering them. It's not bad for the diode, in fact it probably will contribute to a longer life, running them under spec, keeping the temperature down. On the downside, it means that you won't get the full potential out of the diode.
After running my DVD laser for a few days or so at 2.4v and with an average output in the 115mW range, I decided I wanted more power. My design still constrained me to using rechargable batteries that were fixed in place, so I couldn't just switch to alkalines and call it a day. Instead, I added a third NiMH cell - for a total of 3.6v instead of 2.4.
Now, 3.6v is the nominal rating, when fully charged it could be pushing 4 volts, and I didn't want to fry my laser, just pump it up a bit. Still not worrying about a proper driver, doing things on the cheap and simple, the easy answer was... Add a silicone diode in series! Silicone diodes like a 1N4001 have a forward voltage drop of 0.6 volts. 3.6v - 0.6v = 3.0v! So nominally that will give me a full 3 volts to the diode. And when the NiMHs are fully charged, I might see 3.4v to the diode but that's about what it'd get with brand-new alkalines.
Certainly, a proper driver board with current limiting and voltage control would be ideal, and there are definately lots of options out there if you want something like that. Check Sam's Laser FAQ for diode controllers if you want to go that route. For me, I guess I'm just a risk-taker ;-)
Here's an updated schematic, showing the three cell battery, the 1N4001, and the DC power jack used to charge the laser:
The last step is to pick a case and put it all together. Or maybe
that's the 4th step? The case will dictate what size / kind of
batteries you can use, or the batteries will dictate what size of case
The cases I went with are plastic, just over 4 inches long, about 1.5 inches wide, and 1 inch high. My design was to use AA sized batteries but my case is too small for conventional battery holders. So I went with solder-tabbed batteries, and permanently mounted them in the case. So they can't come out to charge. So I added a DC power jack, to allow me to charge the batteries in place.
I used a little bit of bread-board to solder my switches, LED and resistor to, and then just soldered everything up into the case.
I like the layout so much that I have built four lasers into this format now: the DVD diode one, plus two from modules bought from AixiZ Lasers, and one from a green laser pointer I got from ebay and then destructively dissassebled. I will continue to use this format for any other handheld lasers I build, that can be fitted into this size.
Here's a closeup that shows the little circuit board:
Here's a group photo. - four homemade portable lasers, plus a fifth empty enclosure waiting to go:
All-in-all I'm very happy with the results. I have and probably will continue tinkering with it, there's still a wee bit of space left inside the enclosure so I might still be able to pack a bit more functionality in there somehow. From a pure output standpoint, plain and simple, it rocks. It was also a great learning experience and something I can be proud of: I made it myself.
There are some concerns of course about the longevity of the diode; I know I'm pushing it a little hard and I know that sooner or later it's going to cook off and die. Running on the three cells (3.6v) it gets hot after about 60 seconds so I have to impose a duty-cycle on it. Running at 2.4v I ran it for several minutes and it stayed cold. Still, it's a risk I'll take, considering what little it cost me.
And now, here are the specifications as of 12 September 2006:
Laser Diode Characteristics
Power Supply Characteristics
Here's a picture of the inside of the laser:
The information presented above represents my own results obtained with one single diode taken from one DVD player. I am not an expert just a dedicated hobbyist. These results are not guaranteed and you may find your own experiences to be different. In other words,
Note that at these power levels, protective eyeware should not be considered optional - it's a must!