DAMN IT!!!!!! i think i just screwed my diode :'( :'( :'( :'( :'( :'( it was really bright, and the awesomest colour, and it smoked electrical tape really close, but then it just went dim, and started to heat up :'( I JUST TURNED MY DIODE INTO A EXPENSIVE LED :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :-/
oh well, just have to get another and try again, it was fun while it lasted, and i love the little box you sent it in senkat! hope you guys have more luck!


:'( :'( :'(

wow that's alot of smilies ;D ;D ;D

A lot of smilies??? Looks like a lot of weeping to me.. :'(

Ahhhhhh...damn. Well get another one...don't give up. Any idea what happened.

not sure just yet? i think i got a faulty diode, i want a new one senkat > ;D ;D ;Dj/k

TURD ! LOL !!!

Man can't wait until mine arrive so I can screw up too!!

How much current were you running through that diode when it blew up?

I'm still trying to find out the actual blow-out point for these, but don't feel like destructively testing too many of them to find out

lol i bet he wasent using a circuit lol and just using AA battrys

things, welcome to the club buddy! Don't feel bad... you have to break some eggs to make an omelette ;D ;D

Ben, I think Mike will probably chime in with enough info about blowing out diodes at their maximum ratings... But from my personal experience... I pushed one up to 600mA and lit a match instantly from about 20 feet away... ;D I had it running for less than a minute total and I now use it for testing drivers. It still works, and still burns like hell. THANX SENKAT!

By the way... I had that thing cooled like a block of ice to pull that off

--DDL

How did you cool it D?

600 mA sounds like a lucky shot to me really - most of these diodes would fail way before that, right?

(Actively) cooling the diode obviously helps increasing light output for a given current (accoding to the datasheet at least), but does it also allow operation at higher currents before it fails?

I'm trying to figure out an upper safe limit for these things at ambient temperature... that is just using a (big) heatsink, but without TEC's and the like to bring it to really low temperature. Currents above recommended limits in the datasheet will reduce life, but that's no big concern to me within certain limits - just trying to prevent the instant 'poof' while getting good output power.

According to Sam's Laser FAQ, active cooling will increase efficiency but may not prevent COD.

Qutoe from FAQ:
"However, the limiting factor before the LD changes into a DELD may still be Catastrophic Optical Damage (COD) and its onset will depend on the E/M field interaction at the output facet, something not affected very much by ambient temperature. So, your 5 mW LD may still be limited to 5 mW even if it is more efficient at low temperature. "

"Ammo" would be expensive, but it's been an idea for a while now kicking about in my head to have a "semi-automatic laser" that has diodes like cartridges in a magazine, or a revolver or gatling-like configuration, where you overdrive them insanely, and it just mounts a new one each time the old burns out, or drops below spec.

Have it all electrically driven, and run by a PLC where a photocell in the driver circuit activates reloading when the output falters or falls below spec. Or even simpler, just have green/yellow/red beam output status LED's and when it drops to red, the user retracts a bolt, or racks a slide to load a new diode.

Each "cartridge" would consist of a diode in a Aixiz-style optical housing. Maybe have the magazine refrigerated with a peltier junction to increase the thermal capacity.

A totally ridiculous, complex and expensive idea, but perhaps if scaled up would have some application to the military or certain industrial processes where the expense and complexity would be worth it for size savings, or if a disposable solid-state system would be cheaper/safer than volatile chemical fueled lasers etc.

Benm,
Nobody can really answer your question because all the diodes have different personality's. Some behave better than others, and a few will be freaks...I think the one Daedal ran at 600ma's was a freak. The only thing I believe for sure is they all will behave well when being driven with 160 ma's of current. Now that may not sound like much, but it will burn like hell and last a long time.

I will admit I am jealous... ;D A match light at 20 feet is very impressive...so far the best I have been able to do is 8 feet.

I think that should hold true for the COD failure mode, although peraps the facets can actually deal with more light when at a lower temperature. COD is still a (partly) thermal process, albeit at a very specific spot in the whole laser.

The other way these things fail should be remedied by cooling though, degeneration of the junction just as it happens in (overdriven) LEDs.

I'm not really sure which failure mode is to blaim in these diodes though. The really cheap 5 mW reds are destroyed by COD with little exception, but i have my doubts for the GB diodes since some people have been able to push them to enormous powers using TEC.



Err... it would probably be more effective to fling aixiz housings at your enemy, with or without laser diode installed ;p

A nice big TEC and a frozen block of Aluminum. It might have been a freak diode, but it works nicely still ;D

--DDL

Ben, I agree about the COD factor. It living through it makes it really astonishing to me. It really probably wasn't much more powerful than running it at 300mA, and probably only a couple mW more powerful. The excitement was actually keeping it alive for as long as it did, and still have it running to this point ;D

I personally am very amazed at its ability to sustain massive abuse and stay alive. I'm right now trying to figure out the best power for pulsed operation.

--DDL

Daedal,
Was the match sharpied... ;D Was it a safety match????? More info please... ;D I must now try for 21 feet.. :P

;D

it was a sharpied safety match. The only ones I have are red matches and no matter how hard I try never lite up unsharpied... :-?

--DDL

I have the same matches and it lit right up at 8 feet....unsharpied...

Probably not the same matches... I couldn't get it to lite up from 6 inches with a 250mA drive and the laser is the size of a needle tip....

--DDL

Interesting...I have been able to get a white headed match to light easily at a foot with 250ma's. And with the GB diode.

Maybe not ones that are 2 years old, have gone through all kinds of Florida humidity and weather, and perhaps not the same brand. The ones I have are rather hard to lite, even striking it against the book itself... I think I need a replacement soon... ;D What to do with the 500 matches I have still...

Hmm... : I got it! I'll just make a really long line of matches and lite them all at once... ;D ;D That'll be fun!

--DDL

Perhaps, i have no method to measure output power, so i can't create a decent current-vs-power curve at all, and just go by the one in the datasheet. That seems to go straight up to 250 mW and over though.

Running at 220 mA i was able to light a brownish-headed safety match about 5 feet away with some effort.

Also, i find the relation between temperature and power at a given current quite noticeable. When i dial in 180 mA for example, i notice the power dropping in a few minutes because the module heats up. There is no damage though, when i allow it to cool it works as well as it ever did.

Hey -- someone pushing the limits !!!!

I pushed a GD LD to 500 mA but I discovered that after about 350 mA, the output increase has leveled off and added mA's do little for increased output. There is a knee in the Po vs mA curve. Pass that and all you get is mode hopping and DEATH of the LD I pushed one of SenKats GB diodes repeatedly to ~500 mA and found out that I had a defective diode !!!!!(joke)

Some of them will be better than others but over 350 mA appears to severely limit life. Again -- When exploring the outer limits, watch the meters. When you see a leveling of output or visually see the spot blur (mode hopping) ----
Turn it down NOW.

Mike