DVD burner diodes - results posted in gallery

[buffo]

Hey everyone...

Well, I finally got around to playing with those DVD burner diodes that I bought off "littlealgei" on E-bay a couple months ago. ($60 for three modules, complete with the optics and stuff.)

I built my own version of "Sam's laser diode test supply" which is described in Sams Laser FAQ. It uses two LM317's to give you roughly 250 ma max current from a 12 V regulated input. I decided to leave the permanent ma meter out of the circuit, and I also omitted the final capacitor after the current meter. I used a small regulated power supply that I got off E-bay to power the thing. (The supply gives me +5 and +12 volts, but I'm only using the 12 volt side.)

Anyway, after checking that everything was working correctly with a dummy load, I hooked up the laser diode and powered it up. The results were - underwhelming....

I couldn't get a reading on my lasercheck. I couldn't even get a beam! The output looked more like an LED than a laser. (And a dim one at that!) I played around with a few lenses (including the one that came with the DVD module itself) but I never could get anything beyond a dot focused at less than a cm away from the DVD module lens. (And even that dot looked pathetically dim...) I couldn't seem to get a parallel beam no matter what I tried.

Furthermore, the power output is pathetic. I actually took some pictures of the thing in operation so you can see what I'm talking about.

Here is a picture of the module running at around 93 ma. If you look really close at the left arm (red) of the clamp-on volt meter in the picture you can just see the light being given off by the diode.

This is a picture of the diode at the same power level, but with the output end facing the camera. Looks pretty lame, doesn't it?

Finally, here is a picture of the diode facing the camera with the current turned up to around 119 ma. I didn't want to go too much farther because I've been told that these things start to peak at around 135 ma, and I wanted a safety margin. Still, even at 119 ma, the output is a joke...

I'm not sure yet if I just got a bad diode, or if the beam quality of these things is really so bad that this is the best I'm going to get. Either way, I was dissapointed... I've got two other whole modules to play with, and I still have the read diode from this module to try yet. However, if this is typical of the performance of these units, then I won't be buying any more of them...

Adam

[marconi]

Looks like static killed that one.. It should be brighter.
I dont think you have had time to overheat it yet !

Those are too much trouble to mess with as they may not have much life left in them to begin with :cry:

That diode is now a "DummyLoad" good for testing.
Hopefully the next one will work better...

[liteglow]

wery weak :roll:

When I did open my PS2, and fake the laser to belive that it was a CD there, the laser was DAMN bright !
my guess maybe 60-80mW , but I think it will be hard to use the entire PS2 as a power supply hehe

When i check the laser LED it`s not just 2 pins .. one + and one GND..
Oh now. there is like 5-6 pins to connect :roll: :roll:

I still have my PS2 undisambled to figure out if it`s worth fixing (it`s only the power button that is broken lol)

But BUFFO, i have promised you the Laser when i find out to trash the PS2.

So you find out a power supply to the laser when that time comes....

[liteglow]

btw: if you really really want a red module !
I got this 10mW and 100mW that I did buy from aiXiz that i dont need

if you want to buy...

[chw9999]

Just asking - maybe that guy who sent you the DVD diodes got them mixed up and sent you the IR diodes instead ;-)

But since you power metered them...

However, the "optics" from the DVD burner (that is, the alumium part) in which the diode is built in usually does not provide a parallel beam, so your powermeter might be not reading a "beam", mere a blob (and hence showing no reading)....

Do you have an IR sensitive camera at hands?

Just an idea,
Cheers
Chris

[buffo]

Well, after a long talk with Astroguy, I think I know what happened. As Marconi already suggested, it appears that I might have killed this diode with static. I was not being very careful during the disassembly process. I had assumed that these diodes were at least as robust (static-wise) as your average CPU. Aparently that is not the case!

Astroguy suggested that I wrap some very fine wire around the three pins on each diode, shorting them, before removing the diode from the metal mount. He also suggested using a static-grounding strap. Honestly, I've never used one of those things. And I've handled all kinds of chips, from MOSFETs to ZIPs, and never had a problem with static before.

But evidently laser diodes are a little more sensitive! I've got two other modules left to play with, and I'll be sure to take extra precautions with them...

chw9999:

Nearly all CCD-based digital cameras will react to near IR. (Unless you've got one with an IR filter...) Since I used a digital camera (and a cheap one at that) to take the pictures of the diode in operation, it follows that if the diode was giving off significant IR my digital camera would have picked it up.

What's more, I've discovered that a little IR can really skew the power reading on a Lasercheck wand. (Makes the power read a LOT higher than actual.) So if I was getting IR I should have had significant power readings.

Your point about the optics is well founded. Astroguy admits that it's rather difficult to get a good beam out of these units, even with the proper lens fitted to the output. Still, if I was getting any real power out of the diode, even if it wasn't focused, I still should have gotten *some* power reading on the lasercheck.

I think I just toasted this diode. Either that, or it was DOA to begin with. But no matter; I'll be more careful with the next one, and hopefully I'll get more light out of it! (Hey, at least I got the stupid diode test circuit to work!) Plus I now have a true "dummy load" with which to test other drive circuits with! :lol:

Adam

[buffo]

Well, for those of you that are still fooling around with these DVD burner diodes, I found some cool information that ought to be of some help...

Have a look at this.

The website was put together by Robin Bowden, and he's got some great information on how to safely disassemble the DVD modules. Furthermore, he's got a DVD diode driver curcuit that he's put together that supports both TTL and analog blanking!

I've invited him to PhotonLexicon to have a look around... I'm hoping that he'll join up - he sounds like a nice guy, and he's certainly got some good information to share.

Adam