Care for DVD burner laser diode

Hi all,

I'm new to lasers & have some questions about lasers. I've salvaged some DVD diodes, but due to my ignorance I've lost most of. Though I don't know what is the exact cause to ruin it. Some quest in this regards.

How crucial static electricity & what care should be taken ?
Is LM317 driver (mine attached) require voltage regulation too ?
Does laser module require/essential ? and if any alternative to it ?
What is the general DVD burner laser diode current limit ? because I lost most of my diodes while testing under 200ma current.

I always check diode with LM317 module & always within the range of 50ma to 150ma. If I'm not wrong my LM317 module can't deliver more than 250ma (LM317 formula-> 1.25/R i.e. 1.25/5 Ohm. = 250ma) in least case. Is that right or I miss something?

Some story about my diodes. Some I've checked & was working OK, after day or two I check it & its gone not even illuminated !! Even handled with care, I don't understand the cause. Some gone to LED while testing even under 100ma.

In one interesting case when I power supply the diode, it illuminate bright and within second it start dimming & stay at less than LED level light. Same thing happens again & again in next checking. Is that even gone ? I've replace batteries, use 9V/12V DC adapter, built new LM317 module but same thing happens.

Pl. tell me all the required care I should be taken to save my diode. I plan to use this for hobby purpose CNC engraver. I am about to finish my DIY CNC machine & want to use it with DVD laser.

Hi! I had some great experiences with reds from DVD-RW drives, lost 20+ LD's!

So, answering your questions:

How crucial static electricity & what care should be taken ?

Click to expand...

I never taken care of static eletricity, this can be the reason for some LD's death, but I can't say it with sure.

Is LM317 driver (mine attached) require voltage regulation too ?

Click to expand...

No! The LM317 accepts any input voltage between 5V ~ 35V, more voltage, more heat! I never used any voltage regulator for my LM317 drivers.

What is the general DVD burner laser diode current limit ?

Click to expand...

I ever used 415mA for 650nm laser diodes from DVD-RW drives, it runs fine with good lifespan and generally 250mW output power! Use a 3 Ohms resistor for it!

I always check diode with LM317 module & always within the range of 50ma to 150ma. If I'm not wrong my LM317 module can't deliver more than 250ma (LM317 formula-> 1.25/R i.e. 1.25/5 Ohm. = 250ma) in least case. Is that right or I miss something?

Click to expand...

That's right! I use a 10R resistor to test unknown LD's, it give 125mA wich are safe for reds and infrareds.

That's my recommendations, take more care with open cans, since the die is exposed, is much more sensitive than closed cans!
Before you proceed, walk barefoot on floor, it will discharge the static grounding your body.

In one interesting case when I power supply the diode, it illuminate bright and within second it start dimming & stay at less than LED level light.

Click to expand...

Let's take a look at your driver:
- Are you using a trimpot/potentiometer? It may be overheating, increasing the output current, already killed many LD's because of this, if you already know the current that you wan't, use only the proper resistor on it! If you're lucky, the output current dropped under the LD's lasing threshold, and the laser diode isn't dead.
- Add a 470 Ohms resistor between the laser diode pins (driver output), it will automatically discharge the output capacitor for you, so, no need to do this manually.

- Use a heatsink on your LD's! Most of the laser diodes from DVD-RW comes with a rectangular housing with a flat surface. So, you can use a thermal compound and attach it to a heatsink, for testing purposes, you can use a small heatsink.
- If you'll use the LD extracted from it original housing, verify if it is correctly press fitted into the module before you proceed!

What laser module are you using? If you aren't using one (as I do), how are you heatsinking the LD? If possible send a photo.

Good luck! :umbrella:

I have killed laser diodes with ESD. I have also killed MOSFETs and ICs the same way. You should
wear an ESD strap at all times when handling laser diodes. Here is some required reading.

http://laserpointerforums.com/f51/diodes-compilation-all-diodes-data-one-thread-45042.html
http://laserpointerforums.com/f44/learn-mistakes-can-happen-anybody-50044.html