New high power 405nm diode?

[Spyderz20x6]

What I don't get is why Nichia would sell these for such a cheap price rather than a couple thousand :-?

 

[IgorT]

I don't understand what you mean.

Nichia doesn't sell these to mere mortals at any (reasonable) price.

You can't buy this diode from Nichia. But a big laser show manufacturer can, and they get them cheap, cos they buy many at once. It's the laser show manufacturer, where Susie found these. And even they don't want to sell them too much. They are only willing to sell 100 at once - a full tray.



Anyway, i have the Nichia and the 6x at the same power now, and i'll let them run, see what happens.

 

[Spyderz20x6]

I don't understand what you mean.

Nichia doesn't sell these to mere mortals at any (reasonable) price.

You can't buy this diode from Nichia. But a big laser show manufacturer can, and they get them cheap, cos they buy many at once. It's the laser show manufacturer, where Susie found these. And even they don't want to sell them too much. They are only willing to sell 100 at once - a full tray.



Anyway, i have the Nichia and the 6x at the same power now, and i'll let them run, see what happens.

Oh, I see...

 

[Xplorer877]

So as it stands, I understand more testing is needed to confirm your tests, I think these will do swimmingly in a GB. There are many of us who will like the idea of buying a new diode. The harvesting process can be intimidating to first-timers.

Does this seem about right?

130-150mW - for reliability
150-170mW - for a decent life
170mW+ - hours

Since these have a slope efficiency of about 1 than the expected output in mW is about the same as the current they are fed in mA correct?

Is it possible that the kink you're looking for is simply nonexistent at survivable currents?

I wouldn't push it till you get some more. Good Work! ;D

-Tony (my real name lol)

 

[danq]

( 6 x 6X arrived today ;-) )

 

[IgorT]

6 x 6X arrived today ;-)

Haha, i can actually see the excitement in them smileys..

Enjoy!

 

[IgorT]

So as it stands, I understand more testing is needed to confirm your tests, I think these will do swimmingly in a GB. There are many of us who will like the idea of buying a new diode. The harvesting process can be intimidating to first-timers.

It's funny... To me, it was actually more intimidating, to touch a virgin diode..  ;D I hope you have ESD bracelets..

Otherwise, i'm sure they would do nice in a GB. But since only 100 can be bought at once, some people may want to buy several in one GB. And they would want to know for sure, what they are getting is good. I mean, for me, it's definitelly worth to buy 1 diode just to play with it and learn from it, even if it is expensive. But before i would buy 10, i would want to know for sure they are better than 6x's. Or at least just as good....

The price in a GB would probably be similar. In any case, i will talk to Susie about it, once the testing is complete.

Does this seem about right?

130-150mW - for reliability
150-170mW - for a decent life
170mW+ - hours

Well, those would be my preliminary guesstimates for 6x's. I have to kill multiple, and maybe i can raise the guesstimates a little.

But when i say 130-140mW for reliability, i mean reliability as is required in a scanner for example. Hours pile up quickly there, so the diode needs to last longer than in a pointer.

A 6x at 160-170mW would probably last a LONG time as a pointer, with normal use. Possibly even outlive the users interest.

A 6x at 200mW can still last a long time actually. Surprisingly long. I mean, PHRs at >150mW die in my hands in 1-3 weeks. But my 6x is still alive after many months of heavy use. I usually use the highest power laser the most, and yet it survived many PHRs in a row. It was set to 198mA, where it did 193mW at the start, but ended up at 185mW (degradation).


So the numbers are mostly based on my feeling for now - observing the rate of one 6x degradation at ~190mW... Also on the fact, that with any power after a plastic lens, there is around 29% more actually being put out by the diode before the lens.

So when a 6x is doing 130mW after plastics, the actual output power is around 167mW or so... And that's quite a bit. Diodes are not rated for power after a plastic lens. Diode manufacturers don't even know what AixiZ is.. The guesstimates may be a little bit careful, but it's as far as i'd be willing to go, without killing multiple 6x's at different powers first.


As for the Nichia diode, so far it would seem to be very similar, so the same limits may apply. But i will know more after observing it for several days.

Since these have a slope efficiency of about 1 than the expected output in mW is about the same as the current they are fed in mA correct?

No, not at all. The slope efficiency of the tested Nichia is 1.2mW per mA, the slope efficiency of the tested 6x is about 1mW per mA (after a plastic lens, much more behind it), but that's the SLOPE efficiency. And it's the slope efficiency of these two individual diodes.

The slope doesn't start until the threshold. Slope efficiency is mW per mA AFTER the threshold. It is also called "differential efficiency".
If you know the threshold and the slope efficiency of a particular diode, then you can calculate the power from the current -> Po =(Io - Ith) x slope-efficiency.

But every diode is different, the thresholds are not in the same spot, and the slope efficiencies vary. If you want to guesstimate the power, at best you can say it's in a certain range, between the lowest and the highest plot out of 10, for example.

Is it possible that the kink you're looking for is simply nonexistent at survivable currents?

It is possible, which is why i didn't go higher yet. Once i get more 6x's, i will push the old one till i find the kink or it blows.

But it is also possible, that there is a kink, but much higher than anticipated. And if so, and if the kink is any indication of a diode's power capabilities, what would this mean for diodes like PHRs and 4x's? We've been estimating they are rated for 50mW.. But if 6x's were to have the kinks at ~300mW (raw power), could PHRs then perhaps only be rated for 30mW?  :-?

It's strange...

 

[Kage]

But it is also possible, that there is a kink, but much higher than anticipated. And if so, and if the kink is any indication of a diode's power capabilities, what would this mean for diodes like PHRs and 4x's? We've been estimating they are rated for 50mW.. But if 6x's were to have the kinks at ~300mW (raw power), could PHRs then perhaps only be rated for 30mW? :-?

It's strange...

If PHR's are rated for 30mW CW, then we are pushing them to 6 - 8 times their ratings!

So, if 6X and Nichia are that tough, will your graph end at 900mW raw output?

 

[IgorT]

I have this bad feeling about the Nichia... I think i overdid it..  :-/

Usualy, when degradation sets in, initially i always blame it on temperature difference, and i'm not sure, since i'm moving all these lenses back and forth.

It's hard to put my finger on it at this point, but i think the power is already dropping. Is it possible, that an old abused and degraded 6x would outlive a brand new Nichia, of almost the same power rating? The 6x even had to be set higher to reach the same power!

226mW through a plastic lens may have been too much.  :-[ I will set it down to 200mW, a power which 6x's are known to survive for a while, and let it run there till the end.


Kage: Oh, and no.. If the kink position has that kind of implication, then the PHRs really are the only 405nm diodes that exhibit the "fake toughness". The 4x's seem to lack it. I thought the 6x's have it, but maybe they don't. Because i think they pop at under 300mA.

 

[Kage]

I have this bad feeling about the Nichia... I think i overdid it.. :-/

Usualy, when degradation sets in, initially i always blame it on temperature difference, and i'm not sure, since i'm moving all these lenses back and forth.

It's hard to put my finger on it at this point, but i think the power is already dropping. Is it possible, that an old abused and degraded 6x would outlive a brand new Nichia, of almost the same power rating? The 6x even had to be set higher to reach the same power!

226mW through a plastic lens may have been too much. :-[ I will set it down to 200mW, a power which 6x's are known to survive for a while, and let it run there till the end.

Wow, how much current to get the 226mW out of the Nichia?

 

[suiraM]

As Igor said, the interesting question isn't how much power you get for a given current, but how much power you can get out of it for an extended period of time. Some of us are also concerned with what kind of mode distribution we will see at a given power output. I, for one, don't want to have to change a 5-20W array of Nichia diodes too often, if I have to go with a beamjoiner instead of a solid state laser. The cost in time, money and labor would just be prohibitive.

 

[IgorT]

Wow, how much current to get the 226mW out of the Nichia?

"Only" 214mA... The 6x required 236mA to reach approximatelly the same power. The 226mW is after plastic lens of course. I saw it peak at 260mW using the medium FL custom lens, but now it does 258mW, which is what is worrying me a bit. But i won't know for sure, until it drops 2mW more.. But by then too much damage may have been done, so i stopped the testing for now.

My 6x was always slightly lower efficiency. And theoretically, it is possible, that lower efficiency diodes might survive more abuse. If the efficiency was the only difference, then it wouldn't matter. But the lower efficiency has to have a reason. This reason could perhaps be pre-existing imperfections in the die. And if these imperfections are "evenly" spread out, the diode may degrade, but not commit COD. On the other hand, a diode with a near perfect die, when it developes an imperfection at only one spot, and that spot starts growing, at a certain point, it can take the whole diode down in a split second, becase "pressure" is applied real hard at one spot instead of being spread out..

But this is just a guess. I need to test more 6x diodes..... Man, these are some very expensive experiments...


At the start, i wanted to say, that if i had to make a decision now, the 6x would be a safer bet. There, we already know it's an amazing diode. The Nichia seems to be amazing too, but i fear, it's losing power faster than the old, already abused 6x now that i set them this high.. And that's what surprises me. I wasn't expecting my old 6x to take much more abuse. But it just keeps on going.

Fact is, the Nichia i got has a really high efficiency. If the above efficiency/degradation theory is correct, that could be a reason for it degrading faster (if it actually is i'm still not sure, but i never am, when it starts, and by the time i'm sure, it's too late). But not all of them would have this high slope efficiency (1.6mW per mA - no lens efficiency, is actually at the high end).

Maybe a lower efficiency Nichia diode would withstand more abuse, just like my lower efficiency 6x. Maybe i should select a higher efficiency 6x, when i get them next week, and let the Nichia "compete" against that... Another thing is that bothersome intense yellow halo. Again, i don't know if it means anything, because i find it in many diodes, but it could mean the sample suffered some damage at some point.



In any case, 200mW of 405nm through plastics is definitelly an interesting boundary, one that will be hard to reach reliably, and while 226mW / plastic (259mW / medium glass, 273mW / high NA glass) looks much better on a meter, i think it would be a better decision to go down to 200mW (plastic), which 6x's are known to survive for a while, and continue the testing there.

If i put it on one of Zom-B's time recorders, i can start the testing now. I'll put it on the cycler circuit, and let it blast against a photo transistor connected to the time recorder. Then i can do the same with a 6x that will have a graph closer to the Nichia, and compare the end results.

I think that's the best way to go, to get the most out of this experiment...


It's definitelly a good diode. Nearly the same power rating as a 6x, but there could be differences in how much they can take when overdriven.


Also, i used to think, that rounder beams are an indication of a higher power diode. But the so called "12x", which turned out to be a HD-DVD reader diode of a lower power than a PHR, also had an extremelly round beam. Maybe it was a Nichia diode as well, i don't know...


Anyway, i'll continue the testing at 200mW, before i do too much damage.

 

[suiraM]

Do you have a spare webcam, Igor?

I picked up a cheap webcam, removed the lens and stacked some ND filters on it.

If you attenuate the beam enough to avoid saturating the chip (you want the yellow halo to appear yellow, and the laser beam should only show a few maximum intensity white pixels), and mount the diode close enough to capture the halo, you can set it to record a video at a low frame rate. The output power is easily calculated from the pictures if you just measure the output once before you put it in front of the webcam. Make sure you ask the software to give you raw RGB images, not compressed ones.

When you run the video at high speed, you can see the diode degrading slowly, and you can keep an eye on the halo to see if it shifts around or not. The halo is due to locally high indium concentrations, which don't have enough feedback to lase. Shifts in the beam would indicate defects moving around.

If you have a webcam with appropriate chipset documentation, I could probably write you a quick VB program to allow you to track the power output on your PC while watching the degradation. That's as close to a beam analyzer as one can get on a cheap budget, and probably a better tool for monitoring degradation and such.

 

[IgorT]

I do have a spare webcam, which i don't use. No idea about the chipset documentation tho.


But i need to start trusting my instincts. The diode is degrading for sure... Not that i would expect any diode available so far to survive 300mW raw output!

But i am surprised that a veteran 6x is apparently holding up better under the same level of stress..


As intriguing as your proposal is, the important thing right now is a lifetime test, which can be done with my usual methods. It would definitelly be interesting to see what is happening on the inside, but what interests me the most at this point is which diode is tougher - a 6x or the Nichia.

So i'm afraid it's the cycler for this diode..


As for the 6x, i'll just leave it as it is. I have enough 6x's on the way to test their life at 200mW, why not use this one to see how long they last when really pushed?

It's doing 260mW through the medium custom lens at the moment!


EDIT: Ok, i set the Nichia to 194mA, where it is doing 201-202mW (plastic lens). This is where i will continue the testing till the bitter end.

 

[CRFultz]

I have enough 6x's on the way to test their life at 200mW

Are these the one's were waiting for?
I still have that high power blu-ray itch that needs some serious scratching.
I bought a couple of blue lasers from a forum member that will pacify for now but I'm anxious to get that 6x.
How long will the testing take?

waiting patiently
Chuck

 

[hydrogenman15]

I do have a spare webcam, which i don't use. No idea about the chipset documentation tho.


But i need to start trusting my instincts. The diode is degrading for sure... Not that i would expect any diode available so far to survive 300mW raw output!

But i am surprised that a veteran 6x is apparently holding up better under the same level of stress..


As intriguing as your proposal is, the important thing right now is a lifetime test, which can be done with my usual methods. It would definitelly be interesting to see what is happening on the inside, but what interests me the most at this point is which diode is tougher - a 6x or the Nichia.

So i'm afraid it's the cycler for this diode..


As for the 6x, i'll just leave it as it is. I have enough 6x's on the way to test their life at 200mW, why not use this one to see how long they last when really pushed?

It's doing 260mW through the medium custom lens at the moment!


EDIT: Ok, i set the Nichia to 194mA, where it is doing 201-202mW (plastic lens). This is where i will continue the testing till the bitter end.

Didn't you say that hot diodes could last longer then cold diodes? The 6x got less efficient over time and is
it possible that might actually help it? <-- I'm not so sure about that but i thought I might ask you.

--hydro15