8X Diode Murder fund

jayrob · Nov 12, 2009

IgorT said:
And i was just about to post something...

Heck, i'm still going to...

I have to say, it's a good feeling to see 1000+ counts on the display!

The pic was taken at 17h15m ON-Time (over 40 hours total inquisition time, with breaks and re-plotting interruptions)..

Right now we're at 17:41 total ON-time...

If you use your laser three times a day on average and observe a duty cycle, this is already a year of use!
Of course actual average "normal" laser use is very hard to estimate! I'm thinking i should try to jam at least one of those time recorders into one of my lasers, and preciselly calculate how much i use my favorite lasers on average...

The most interesting thing would be if i could put them in some of the lasers i make for others, and then after a certain amount of time get them back and read off the actual usage time.

I wonder if Zom-B still has any of these available, and if any of the 8x GB participants would be willing to participate in an experiment like that!
With some of the larger lasers, the time recorders would be easy to incorporate (and easy to remove by the user without having to return the entire laser)...

In any case, i have to say these diodes are pretty tough!

I'm staying up approximatelly until three in the morning to make a 20h degradation plot...

Great work Igor...

Thanks for keeping us updated too!

Krutz · Nov 12, 2009

..things look brighter now!

igor, dont stay up just for plotting, ok? get some sleep when you need it! we have already a lot of fresh data and all. all a lot appreciated for sure!

manuel

bryce007 · Nov 12, 2009

IgorT said:
The most interesting thing would be if i could put them in some of the lasers i make for others, and then after a certain amount of time get them back and read off the actual usage time.

I wonder if Zom-B still has any of these available, and if any of the 8x GB participants would be willing to participate in an experiment like that!
With some of the larger lasers, the time recorders would be easy to incorporate (and easy to remove by the user without having to return the entire laser)...

I'd totally be down for that. In fact, I'd like one of those on all of my lasers. Is it just a little device that will connect to the driver and record the usage time? That sounds very interesting

IgorT · Nov 12, 2009

Thanks Jay!

Well, many people contributed to make this happen, so i want to make sure they get as much as possible in return...

Otherwise, our first murder candidate is nearing the 20h mark! Only 40 more cycles to go! :yh:

This morning it was trying to pretend it became resistant to torture... Almost as if it got used to it.

I'm anxiously waiting to see what it will show at the 20h mark... 80 more minutes and we'll see..

IgorT · Nov 12, 2009

Krutz said:
..things look brighter now!

igor, dont stay up just for plotting, ok? get some sleep when you need it! we have already a lot of fresh data and all. all a lot appreciated for sure!

manuel

I have to make evenly spread out degradation plots. If i don't wait up and re-plot it now, the only alternative is stopping the cycler... And i don't want to waste a whole night of cycling.

Besides, i'm working anyway, it's not just the Torture Chamber keeping me up...

daguin · Nov 12, 2009

He's enjoying this way too much, isn't he?

Peace,
dave

IgorT · Nov 13, 2009

daguin said:
He's enjoying this way too much, isn't he?

Peace,
dave

No, i'm just doing it for "science"... :angel:

The counter reached 1204! We are at 20 hours!!!

I stopped the cycler for re-plotting....
Let's see what the diode has to say now.. :evil:

Crazy Jay · Nov 13, 2009

Hey IgorT, Did you test what wavelength each diode is? It would be nice to know the highest lowest and average.

LarryDFW · Nov 13, 2009

Igor;

Sharp"s definition of Blu-Ray diode "end of life":

product life ends when the drive current reaches 1.3 times the initial value under pulsed operation

So playing with your initial power graph @ pulse power (250mw),
and drawing some new 30% lower power lines,

this looks to be ~ 25% power loss at the same current (220ma).

LarryDFW

IgorT · Nov 13, 2009

Ok, the 20h degradation plots...

There was no obvious drop from 10 to 15 hours, but 5 additional hours of ON time left their mark... The difference does not seem larger than that from 10-15, even tho it's the result of 10h of ON-time (20h of cycling)..

Anyway, attached are the plots, the diode already prooved it is tough, we shall see how much longer it can take this kind of abuse, but i'm already impressed... :yh:

Other data:
Ith is at 36mA
Po @ 300mA is 339mW
Slope Efficiency dropped to 1.275mW/mA

P.S. I think in one of the previous reports i measured 37mA for Ith, but Ith is kinda hard to determine. I usually simplify it by recording the value where the power reaches 1mW, even tho lasing actually starts sooner...
Measuring Ith is made a little harder by the fact that spontaneous emissions also register on the LPM, so i try to dial in just under the lasing threshold before zeroing in my meter, and then raise the current until i see 1mA...

There are some errors always involved, and they are the most apparent at such low numbers. Higher up the numbers become much more accurate.

P.P.S. This is it for today, i have a bunch of work to do, i will measure power after another 5h of ON-time, but unless it's drastically different (indicative of a kink), i will not replot the diode until 10 more hours of ON-time...

bryce007 · Nov 13, 2009

Thanks for the update! Great work!

Crazy Jay · Nov 13, 2009

Cool. So after 20 hours its still kicking out 360mws at 320ma.

IgorT · Nov 13, 2009

LarryDFW said:
Igor;

Sharp"s definition of Blu-Ray diode "end of life":

So playing with your initial power graph @ pulse power (250mw),
and drawing some new 30% lower power lines,

this looks to be over 25% power loss at the same current.

LarryDFW

Yes, i remember reading about that from another manufacturer, but it applies to diodes under normal operating conditions.. The way we overdrive them, they probably never get to degrade as much as to require 30% more current to reach the initial power.

The most i've normally seen a diode degrade was approximatelly 5% in terms of power (lost 5% of it's initial power before LED'ing)...

There was only one exception i have seen so far. A low efficiency PHR degraded by over 50%! It still had almost 40mW, but it's beam was completelly deformed by that point!

We shall see how much these can degrade before dying, being overdriven like this....
Since i have actual numbers, i can calculate how much current it takes to reach the initial power at each of the measured steps.

Which reminds me. I forgot to mention some numbers in the previous post.

IgorT · Nov 13, 2009

Crazy Jay said:
Cool. So after 20 hours its still kicking out 360mws at 320ma.

Yes, i measured it at 363mW at 320mA... It started out at 382mW at 320mA..

It's quite a considerable drop there! Of course if i was cycled at 320mA the drop would have been higher, or worse, the diode dead..

I think it's already safe to say this diode won't get to see 100h.. But on the other hand, i'm not that worried about that anymore... I think i was overestimating my own laser use as well..

Since degradation is this noticable, and i don't recall people mentioning such power drops on their 8x lasers (of course i don't get to read as much of the forum as i would like, so maybe i missed it), i'm guessing that we don't really use our lasers as much as i once calculated (or should i say guesstimated)...

I really need to do some ACTUAL average usage measurements.. I already said i'd try to squeeze one of those time recorders into my most oftenly used laser (which will be my 8x), and Bryce also said he would like to have one in his 8x..

Since his is a Kryton, getting it in will be relativelly easy, and after a few months, Bryce can just cut off some wires and send it back to me...

I'll also try to get more time recorders, perhaps Zom-B still has some left....

That would help make more sense out of all these numbers!

HIMNL9 · Nov 13, 2009

@ LarryDFW:

But keep in mind that, usually, the definition of "end of life" from manufacturers, is normally referred to the "useful life for the planned use" that they do ..... and that this is normally referred about when the power go 30% less that the tag power ..... (and also that we are over-use and oer-abuse those poor diodes

)

Wondering if using one of these 8X at 270 / 280 mA, well heatsinked, can grant you around 300 mW for 100 or 150 hours (that is not exactly to throw away

) ..... and also if degrade a bit in all this time, is not too much bad as result

Edit: if i only had enough money, i may be tempted to take one of these diodes, set it at 300 mW output in a decent host, turn it on, and record time, power out, VF and temp until it die, for make a plot ..... so, i can say that, luckily for me (and for the diode

), i don't have enough money for that

bryce007 · Nov 13, 2009

IgorT said:
I really need to do some actual average use measurements.. I already said i'd try to squeeze one of those time recorders into my most oftenly used laser, and Bryce also said he would like to have one in his 8x..

Since his is a Kryton, getting it in will be relativelly easy, and after a few months, Bryce can just cut off some wires and send it back to me...

I'll also try to get more time recorders, perhaps Zom-B still has some left....

That would help make more sense out of all these numbers!

Kewl! Yea if they are a reasonable price, I'll probably take like 5 of them. Keep me posted

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