I've had a very productive evening in the workshop; picked up this DVD burner today for AU$26, 24X, I thought it was worth experimenting with even if it was a pain in the butt.





I've pulled apart a few DVD drives now so it went smoothly, the sled looks pretty standard, with no PBS cube, but some nice optics I'll have to experiment with later.



Locating the 650nm diode mount was easy enough and I didn't panic when I saw the odd shape of the cast, molded heatsink, I've been reading the posts here detailing other members adventures with these types of diodes so I knew what to expect.



An interesting little optical element with some kind of plastic filter is mounted right on top of the diode window.



This is a three pin diode molded into an odd shaped square heatsink.





I tuned a driver to 100mA on 3v and cautiously made an educated guess about the wiring order - looked similar to one in another post so took a chance and tried the same wiring - bingo! Worked first go, lovely colour. My first thought was, seems shorter wavelength than 650s I'm used to (?) Wish I had a spectral analyser.

Next, I took a nice big pair of wire cutters and proceeded to very carefully nibble at the housing to create a smaller, squarer block, something I could mount in a aixiz module. My patience paid off, the brittle alloy heatsink broke away cleanly leaving me with a rectangular block shaped diode. So far so good!



My heart missed a beat when I re soldered the wires and checked it on the driver, no lasing, then... I'd unplugged the power supply, all good, I hadn't broken it.

Next step - housing. I took a tungsten barrel burr in my dremel (cheap copy of a dremel) and slowly, slowly squared up and enlarged the diode recess hole in the aixiz module, checking against the diode then grinding away more metal until it almost fitted. I was then able to use needle nosed pliers to press the diode into the machined out housing - not a perfect fit by any means but a tight fit with some good points of contact between the diode heatsink material and the aixiz.



I had to press the diode in a bit further after a focusing test with the lens, and then press one side and then the other until it was as straight as I could get it, not easy considering the make-shift nature of the build.



I don't have any thermally conductive epoxy of any kind so I actually used solder - pressing it quickly into the larger gaps with minimal heat and cooling it as fast as possible. Another nervous test with the driver confirmed everything still working fine...

After assembling the aixiz module I disconnected the driver and reset it to 200mA using a dummy load.



Success! I can hardly believe I pulled this off, the thing produces a surprisingly nice beam with good divergence and beam profile. There are some aberrations surrounding the dot and a bit of a "wing" out one side but all in all it's very usable.





I hope this post isn't re-hashing work already done too much (thanks Hemlock_Mike, HIMNL9 and LarryDFW for your tips), and that it's useful to people who are looking to use these affordable, high powered diodes in builds.

Now my question is, what is a safe current to run this thing up to? Is 200mA a reasonable starting power?

people drive the 20 and 22x burner diodes(LOC's) at 400ma

@200ma it will last a LONG time

Just turned the driver up to 300mA. The bloody thing is getting warm (the driver that is), I need a better driver, but the laser is very bright, wondering what mW power I'm getting? The laser module doesn't even get warm at this power - well maybe just warm, certainly not hot.

Nice use of what you have available, Jupiter! I'm borderline too poor for this hobby, but this thread was pretty inspiring

Drivers get warm, mine get hot with the 445nm diodes. Any way, I have an LCC at 500mA for some time now with no problems, this should take alot more current, just get a heatsink, then turn it up, shame you dont have an LPM...

Thanks kingdave2357, I'm new to this hobby but I'm keen to learn. This is a real milestone for me and to be honest I half expected this project to fail. Tonight I'm going to improve the thermal junction between the diode and the housing and fit a heatsink; then I'll crank it up - cautiously though, I'd be devastated if this died after all this!

EDIT: This morning I stole a few minutes and made my own thermal epoxy. I had a little jar of powdered aluminium - I mixed it with araldite (High strength, 5 minute, two part epoxy glue) to make a thick paste and filled the gaps between the diode and the module as best I could with it. This has got to be better than not doing it and relying on the small points of contact otherwise.

The manufacturers of this epoxy state "Bond strength weakens above 65ºC but strength is regained when temperature drops". 65 is borderline hot enough to burn your fingers so I'm hoping this material will take the punishment.

Make sure that the aluminum epoxy isnt shorting the driver output leads together....

Yeah I thought the same thing but surprisingly there is infinite resistance through this stuff. I poked the probes of my multimeter into it on ohms and moved them closer and closer together until they were almost touching - no measurable conductivity through this stuff (at low voltage anyway).

UPDATE: I picked up a nice piece of aluminium from an engineer down the road for nothing - just a dud piece of turning that was in the scrap. I've drilled it and mounted the module in it and am now running it at 450mA. I wish I had a LPM too - checking prices now.

I'm a noob so please excuse the stupid question... Why did you use wire cutters on the housing when you have a Dremal (or copy od a Dremal)? Since you mentioned that the alloy is brittle wouldn't it have been better to cut away the laser housing?

Stephen not a stupid question, but one I have a good answer for. 1. I wanted to avoid vibration of using any kind of saw/rotary tool on the body of the diode - for fear of breaking it, and 2. I wanted to avoid getting metal filings in the actual diode, which would be a serious risk.

Here are a few pictures of the current config.

Sad news.... RIP 24X diode. Gone. Dead. Kaput. I suspect I killed it by driving it with a STUPID little multi-select transformer power supply. I'm angry with myself... this is a crappy non-regulated power supply. I'm certain that's what did it, a spike from that. I'm still grieving the loss of my baby...

I'm going to try again. The project was so successful up to this point. I'm SURE I had adequate thermal contact, enough heat sinking and was driving it at a conservative current... the only explanation is a voltage spike from the transformer... (?)

^ i know your pain, i've lost more diodes than i care to think about

Nice thread Jupiter, very good use of supplies.

Check out hightechdealz.com, modwerx.com and stonetek.org. They all sell specially extracted diodes to save you some time, and at a much cheaper price than buying the whole burner.

Heatsink wise, if you are happy with the bench style you have going that's fine, some people prefer the larger heatsinks if you don't need portability, but if you want it in a flashlight style host, check out jayrob here on the forums, he custom machines heatsinks fit for hosts, he can also pre mount drivers for you unless you want to fit one your self if you buy one from one of the stores.

Another good host maker is flaminpyro, who specialises in copper heatsinks. Ehgemus, is a great machinist, and he puts together hosts that require no modules, so the diodes are directly pressed into the hosts them selves, this offers great cooling and his designs are fantastic

Hope this helps a little info wise.

Sorry to hear about the diode burning out already. Thanks for the explanation on why using clippers is better than a rotary saw. I didn't know vibrations or metal filings could damage the diode. This noob has got a lot to learn!

Well to be honest with you, you inspired me to do a non disection build with a new release of the 815 style diode on a copper heat sink with silver epoxy. Going to try it out!

You've done a good job documenting your experimental module!

Thanks guys, I've learned a lot from this experiment, I have to say I'm hooked on the hobby well and truly now!

Stephen - you and me both! I'm a novice here too, don't take what I say as gospel please, just my thoughts and ideas. I'm thinking if you stuck a small piece of stickytape over the diode 'window' and then carefully trimmed up the heatsink with a hack saw it might be better than using clippers, and potentially crushing the diode? (or having it ping across the room like a bullet!?).

Asherz, thanks for your advice, I'm checking out prices now. I guess the reason I wanted to try the 24X extraction was I expected higher output power - maybe potentially true but not worth the trouble or the pain involved. This is literally and metaphorically trying to fit a square peg in a round hole!

Seoul lasers - go for it! I'm convinced that if I'd used a regulated power supply it'd still be alive. Please post your project so we can benefit from your experience.

Well, with this whole 445nm fever going on, and red is still a beautiful color. I really can't resist stopping and looking at these pics. Really good, by the way.

Nice build !

That's some great work, and I really appreciate the fine photography.

Excellent writeup.. and even better photos!!

There seems to be a trend, and it's not good for us DIYers.. manufacturers are making it harder to extract these diodes. It used to be most of these sleds had closed can diodes that were press-fit into a heatsink. They could usually be easily be extracted. Now more and more of the diodes are 'open can' (saves cost, but not good for DIY builds.. you don't want dust accumulating on the facets of the diode IMO) and are housed in armor-like heatsinks, making extraction much more difficult.

You wisely choose to file the heatsink down rather than attempt to extract the diode proper. A tedious bit of work no doubt

I doubt the diode perished because of your power supply.. you were driving it too hard (450mA). The power of the red diodes in these DVD drives has not increased the past few years. Most of the development is now on t'BluRay' diodes. From what I've seen the majority of these red diodes are not good for more than 1/5 watt power (~200mW), at least if you want a reasonable diode life. Yes you can boost the power, but in nearly all cases this will result in very short diode life. Your initial 200mA drive current was more reasonable.

One way to determine the max safe power is to calculate the 'slope' of the diode at various power levels. You need a DMM and LPM to do this.

For example, Hemlock_Mike did some testing on a DVD diode being offered by StoneTek:
LPC-815 20X DVD burner diode out of sled [LPC-815_1] - $12.99 : StoneTek Electronics, Your Laser Parts Store

See this thread:
NEW LOC Laser diode review.

Anyway, he determined these numbers for the diode: (pretty typical number for these diodes)
Drive Current (mA): Power out (mW)
100: 56
150: 92
200: 134
250: 180
300: 210
350: 226
400: 240
450: 240
500: 237
550: 215

To determine the max safe power, look for the most efficient point of operation. Divide current consumed by power out..

Current (mA): mA/mW (mW per mA)
100: 0.5
150: 0.61
200: 0.67
250: 0.72
300: 0.7
350: 0.64
400: 0.6
450: 0.53
500: 0.47
550: 0.39

Now you can see the most efficient point of operation is between 200-300 mA of current. The lower the better for long life.

Hmm... thanks flogged, good info and it makes sense. I reckon maybe I did push it too hard. I'm learning and I'm already cringing when I think back to the way I treated diodes in earlier builds (attempts).

I've got 3 LPC-815 diodes on order from stonetek as well as some modules from aixiz, and 2 drivers here ready and waiting for them, so I'm looking forward to playing with those. I'll be much more realistic with what I expect from them and won't push them so hard, based on the info above.
Cheers.

Go for better current sources.. good desings will keep current to what you selected regardless of input voltage - at least until you manage to thermally blow out transistors

Or they just plain switch to packages that are hard for DIYers to make use of. For example I have some diodes on my bench at work right now that I pulled out of an A-open burner I think it was. It has the photodetectors integrated inside the can with the diode. The freaking things are rectangular, about a half inch wide and have 12 pins! I ended up decanning one just to figure out the pinout. I had a 50/50 shot of it being the IR since both were identical other than the markings, and google gave me nothing on those. Turns out the one I decanned was the 650. It needed it anyway, as it had some kind of diffraction grating integrated in the can. I had it lasing earlier today at about 150ma and holding up a collimation lens to it but in the weird package, i'm not sure what good even messing with it will do.

In all honesty, these packaging changes have nothing to do with us, and everything to do with profit margins. As long the 5.6mm TO packaging stays cheapest, that's what they'll use. Otherwise they'll switch to the cheapest way to manufacture their product to extract the highest profit margins.

I dont think they care about us at all - there are quite a bunch of people playing with lasers, but compared to the number of laser sleds and drives sold its all negligible.

5.6mm is a conventient form factor mainly because that its what fits in aixiz modules, which are cheaply available. If the industry decides on using different packages from now on, there will be different modules to mount them in. I suppose the 3.5mm round diode housings are a good candidate to begin with.

Open can is something we should get used to - in an optical drive the diode is installed such that there is little chance of dust etc becoming a problem. It should be much of a problem for builders either - the only thing is to get rid of the plastic lens threads and springs.

I used aixiz glass lenses with a layer of teflon (gastec) tape around them to make a nice and secure fit.

Pieces of plastic coming off due to the spring are a problem for diodes in a can too btw - they can land on the output window and melt to it. The diode might still work, but its use is gone.

Can you provide the Pin out for this particular laser ???

Thanks,
Russ

Sorry to bump, any luck with running these recently? I picked up 2 of these same diodes recently, and I want to make some good strong hand held lasers with them.