My first attempt at a dvd laser

After owning a Wickedlaser for some time now, I decided I wanted to build my own DVD laser. I ordered two of these preinstalled sony diode aixiz modules at stonetek (can't post links on this forum I guess), and followed the instructions to make the voltage controller here from Daedal

While I was waiting on the diode to come in I soldered up the voltage controller and verified that I was getting 44 to 375mA of current (I used a 3.33 + 0-25 ohm resistance setup), and everything worked great. Once I got the laser diode in, I hooked it up with a ammeter in series and everything electrically worked just fine, with the same current as before with a voltage drop of 2 to 3V. Instead of seeing a blinding red light, I saw a dim one, that grew only slightly brighter as a I upped the current. To make sure it wasn't that diode or my power supply, I grabbed a 9V battery with a 150 ohm resistor and hooked it up to the second diode, drawing around 60mA of power, and got the same result.

I'm new to making lasers, but I'm a third year college electrical engineer so I know a decent amount about the circuitry. Does anyone have any ideas of what's going on or what to try? I'm going to call Stonetek pretty soon if I can't get it working.

Also, on another note, I'm a little confused about the aixis module. With the dim red light I had, I could not get a decent beam. The further I screwed in the lens, the closer my focal point became, and even with it almost all the way unscrewed I couldn't get a strait beam like you would expect from a laser.

Thanks in advance for everything, I love this forum and have been reading everything on it!

That laser diode is now toast.  That is what you will see when the diode dies.  Looks like a dim led.  I'm going to take a stab in the dark that you were driving more than the required current but since I'm no electronics geuroo, I'm not going to say for sure.  The stonetek diodes require about 130ma-400ma max.  The max being not so much an absolute max.  Each diode carries it's own specifics.  Your wanting to make sure that your driver is current regulated and set specifically prior to attaching the laser diode.  Look for graphs (usually posted by Dr. Lava) that indicate power levels you can expect from a given diode at a given current range.  

Good luck and your well on your way.

Side note. You won't really be able to focus a dead laser diode with the aixiz module. You have to wait until you get some more photons comin from it!!! ONce you do get a functional diode to work in the aixiz you will notice that the beam diameter right at the aixiz is not what you would expect from a red laser. Certainly not like those cheapo red pens as those are setup with a basic focal length and have nice tight beams. Instead your going to see a huge 3-4mm beam exiting the aixiz and get smaller as it goes. You'll have to fiddle with the focus to understand. but smoke helps in getting the beam good.

Thanks for the reply. It looks like my diodes are burnt out, kind sucks I burnt both of them :'(. I guess I'll have to look at my circuit and see what went wrong, and order a few more of them (my "cheap" laser pointer is getting expensive pretty quick, I better not mess up my blue ray one!). Do you have a link to that post of Dr. Lava, I did some searching and didn't find it. I'm thinking about just using a set resistance value for my blue ray laser, and maybe the red one if I can find a powerful/safe current.

After messing with my "less" burnt diode, I was able to focus it across the room. It looked like a typical 5mW red laser with almost dead batteries. The second diode won't even show up more than 3 feet away.

this is an all encompassing graph of all the red diodes that lava has done.

http://hacylon.case.edu/laser/diode_red_roundup.PNG
Now obviosly your looking for the -54 diode

Have you powered down the driver and shorted the capacitor for a good amount of time, prior to attaching the diodes? If there is any voltage built up in the cap higher than the working voltage of the laser diode (2.4-3.0V) then it will discharge it through the diode with high amounts of current. It takes only nanoseconds for optical damage to occur with too high currents. This has been said dozens of times on the forums, if you look around.

Zom-B said:

Have you powered down the driver and shorted the capacitor for a good amount of time, prior to attaching the diodes? If there is any voltage built up in the cap higher than the working voltage of the laser diode (2.4-3.0V) then it will discharge it through the diode with high amounts of current. It takes only nanoseconds for optical damage to occur with too high currents. This has been said dozens of times on the forums, if you look around.

Click to expand...

I'm not sure if there was enough voltage to kill it. At first I was using two AA batteries before they died, but then I realized that wasn't enough voltage to run the controller and diode so I switched to a 9V battery. This was after I already fried them, so I'm not sure if 3.2V could have built up over the cap and then fried the diode first.

I will do some more reading about this before I try with my new diodes when they come in, thanks!

What Zom-B said.

You said you were testing the driver beforehand and everything was great. This may have been the problem though :'(

If the cap isn't discharged before connecting the diode, its a pretty good bet that the cap will toast the diode.

Also, check and double-check the diode pin-out's, just to make sure. Also make sure that when you solder the diode into your driver circuit, that the driver is completely disconnected from your power source. Last but not least, start will full resistance and work your way up. Good luck!

nuclearnova said:

[quote author=Zom-B link=1211944860/0#4 date=1212060814]Have you powered down the driver and shorted the capacitor for a good amount of time, prior to attaching the diodes? If there is any voltage built up in the cap higher than the working voltage of the laser diode (2.4-3.0V) then it will discharge it through the diode with high amounts of current. It takes only nanoseconds for optical damage to occur with too high currents. This has been said dozens of times on the forums, if you look around.

Click to expand...

I'm not sure if there was enough voltage to kill it. At first I was using two AA batteries before they died, but then I realized that wasn't enough voltage to run the controller and diode so I switched to a 9V battery. This was after I already fried them, so I'm not sure if 3.2V could have built up over the cap and then fried the diode first.

I will do some more reading about this before I try with my new diodes when they come in, thanks![/quote]


This may be a dumb question, but did you try hooking the 9v into your driver and cranking up the current? Some of the higher power diodes may just barely be starting to lase at 60mA so it will still look pretty dim. The two AA's would definitely make it look like its dead simply because they cant give the driver the juice that it needs. So they may not be dead after all, maybe they just need a good kick in the pants with a good amount of current.

Thanks GooeyGus, I did have my batteries in with my switch in the off position when I connected the diode, but I'm guessing there was still voltage in the cap. I'm not sure how I could have overlooked something so simple, but I guess its better to learn this stuff now on my 20 dollar diodes compared to my senior design project I'll be working on next year.

After I have the diode attached, I start at around 40mA and work my way up to about 400mA. 40 lights it like a very dim LED now that its toast, maybe 40mA wouldn't lase the thing though. I wish it was just me under-powering it with two AA batteries but I tried everything for two hours and actually verified that I had the correct current driving the thing.

At 40mA it will look really dim either way, but you did eventually turn it to 400mA and its still dim? Its toast for sure then.

nuclearnova said:

Thanks GooeyGus, I did have my batteries in with my switch in the off position when I connected the diode, but I'm guessing there was still voltage in the cap. I'm not sure how I could have overlooked something so simple, but I guess its better to learn this stuff now on my 20 dollar diodes compared to my senior design project I'll be working on next year.

After I have the diode attached, I start at around 40mA and work my way up to about 400mA. 40 lights it like a very dim LED now that its toast, maybe 40mA wouldn't lase the thing though. I wish it was just me under-powering it with two AA batteries but I tried everything for two hours and actually verified that I had the correct current driving the thing.

Click to expand...

Two AA batteries with the lm317 is clearly not enough, you need at least 6v to let around 3v get to the diode.