Ace82 said:
Well...
I have had this happen to me several times... I mean several. I will no longer push my 803T's over 90-115mA because...I guess the laser Gods don't want me to have a blu-ray in the 100mW's... they always die. That's why I'm selling 70mW MXDL's because they will last forever. They were designed to lase at 60mW, and we push them to the limit. If you use your lasers as much as I do, then you never know when the next time you turn it on if it will die...when pushing them this far. So, I keep the current to a comfortable level for these LD's. Once I get my 6x burner, I'll push it to probably 150mA at the most. I've had nothing but BAD experience when pushing these LD's to what I've read on these forums should be safe. They just don't last for me.
It happened on initial turn on right? As soon as you switched it on...LED right? You didn't even get at chance to see it lase before it LEDified right? Maybe if it ramped up slowly we could get more out of these LD's, but going from 0 - 100% in an instant, just causes too much stress on these LD's being pushed to their limit.
Ace, you're not the only one... Far from it...
I went through >70 PHRs by now, and i used MANY of them for destructive testing, trying to figure out the max safe power. And i mean MANY! When i finally cleaned my workspace after a long time, there was like a HUGE pile of dead PHRs there, all from various different high current tests. And i threw some away in the meanwhile!
There is a reason i don't like setting my PHR laers higher than 110mW. And even so i explain to my buyers, that it is risky! That if they want 100% reliability, i would have to set them to 60-80mW... But unlike higher powers, it is somewhat of an acceptable risk...
When i first started testing PHRs, the belief that they can take super high powers was just beginning to spread. I set them to 190mA, LED in an hour, 170mA LED in a week. At 160mA some lived long enough for me to start thinking they will make it! But then they died in two weeks.
During this time i was leaving them on for 60-90 minutes a day (as much as time allowed), while monitoring the temperature. From the days, i calculated they only live around 15 hours, 20 max, if you're really lucky at 160mA. I did find ONE that survived this testing, and is still doing 164mW at 160mA, but even so, i never know what will happen to it.
PHRs just can't take the high powers. And it has nothing to do with heat. They are simply not made to handle the optical flux. It's the optical flux that causes COD, not heat.. Not if you use any kind of heatsinking. In fact, heat reduces the output power, reducing the strain on the diode! It could partially explain why that PHR in nothing more than the tiny sled heatsink lasted so long.
If you barelly use a PHR at a high current, it may "live" long in days, but the hours of actual run time....
Even at 100mW, PHRs can start degrading after a lot of use. I have seen a PHRs, that started out at 105mW, but ended up at 28mW! It didn't die, it just degraded this much! Just now i am testing one, that started at 107mW, two weeks ago it was at 90, then with barelly any use 80, then 70, now it's at 60! And this one is REALLY weird! Every so often it just flickers off to a low power LED with a halo around the dead spot. It looks EXACTLY like COD. But then it comes back! Suddenly it does 55mW again, and then it repeats this cycle! It turned into a LED and back into an LD and back to LED.
I did not believe this is possible. I still don't. But i saw it.
PHRs are really weird diodes. They have this fake toughness about them, that allows us to push them to ridiculous powers. Powers that are probably not good for a GGW 6x in the long run! With reds, if you went too far, you knew it almost instantly. But these... They are ridiculously tough. But they just act tough. You can kill them, and you won't even know it until weeks later. Months, if you don't use them much.
If you use them very little, this fake toughness can make you think it is safe. But if you actually DO use them a lot, like me... Sooner or later they will die. Each is different and they vary a lot so it's impossible to say when exactly, but it's inevitable - the higher you set the power, the sooner it will die. This is true for any diode and there is no way around it.
I used to think this was a 60mW diode. Now i'm not even sure of that anymore. There are some mechanical differences from the 60mW Sanyo, if that's the diode you meant. It could be 60 and we just don't have the datasheet for it.
If these were more like reds, we would all agree on the same max safe power for them. Reds at least had the decency to die if you pushed them too hard. But they are not even close to being similar. Because of that, different usage habbits can lead to different concepts of "safe".
From my experience, setting a PHR to 150mA is similar to setting an open can to 600mA. I did it, and the open can lasted 24 hours straight! But i would never actually set an open can that high, not even for myself.
I have posted my high current test results and a theory on why other diodes would seem to be surviving the same powers months ago. But everyone wants power, people don't want to hear they should set their lasers lower.. Now the hours are piling up, and more and more are starting to die. Mostly people blame themselves for it. They think they made a mistake. Or they blame everything else, but the power. For a while, even i was thinking there is something either wrong with ALL my diodes or my sanity. I changed my test setup, i changed my soldering station, i changed my test heatsink, i implemented a softer startup, i even changed my diode source and my test methods. But the results were always the same.
But DrLava said it from the very beginning - if you're lucky, you'll get 100mW out of a PHR.
I am just glad they lasted long enough for better diodes to appear! However, when everyone expects 130mW minimum from a PHR, what will happen to the 4x's?
What can i say.. I take my hat off to you, Ace, for not letting yourself be sucked into the power frenzy!
I'm starting to think, that even i went too far. And yet, when people look at my laser, they ask me how come i don't know how to make 150mW! :
To the OP: You may have just been very unlucky for a diode at less than 125mA to last less than a month. Mostly you can get some semblance of reliability at 125mA. It should have lived longer than a month. But don't expect it to live forever..
Or maybe you use it even more than i do. In that case you can only get away using a power the diode can actually survive.
I know it's hard to settle for a lower power. When i first saw 180mW of blu, how could i ever go back? I still sometimes set my personal PHR to 160mA. The latest one is doing 170mW. But i don't expect it to take this for very long. 170mW after an AixiZ lens means >210mW behind the lens. We are asking too much of a poor little 40-60mW diode.
BTW, I am not saying that people should not set their diodes as high as they want to. But i do think they should understand the consequences.
