12x Murder Experiment - Take 2 (With 12x Comparison Plots)

[x101xtreme]

What's the criteria for "higher efficiency" 12x diodes? Mine does 600mW at 425mA. Does that count?

 

[daguin]

What's the criteria for "higher efficiency" 12x diodes? Mine does 600mW at 425mA. Does that count?

Compare it to the IP/OP posted here

http://laserpointerforums.com/f38/12x-br-diodes-46798.html

Does yours fall below, at, or above the middle?

Peace,
dave

 

[IgorT]

The diode made it past 50h, currently nearing 60. After 60 i'm spreading the tests out to 20h, because not that much is happening in between. The resolution of the rest of the test will be same as it was with 8x's after the starting hours...


For now, here is a combined report for 30, 40 and 50h.


Degradation speed @600mW (50h elapsed):

When each step is observed by itself, very little seems to have happened.
At 600mW initial Po, the diode only dropped to 98.5% of it's power by 50h. But that's due to the "burn-in" at the lower powers...

But another plot i posted a couple times before started making a lot more sense now - the one showing combined degradation over all steps together in one row...


Total degradation so far (68h elapsed):

From the very beginning, the diode dropped to 95.3% of it's initial Po after going up and down a couple of times.

This second graph looks a lot more like what was happening with 8x's, except for all the bumps. And even tho the test power kept changing over it's initial parts, it is safe to say that the shape of the graph would have been very similar to this, if the power was 600mW from the very beginning.

Only thing different would be, that the first three steps would have dropped somewhat further in the same amount of time. The first step would obviously have been increased the most, and the last step the least, as it's already close to 600mW.


Still, even so i don't believe that graph would have fallen below the light blue line of the first test 8x. Perhaps it would come close, but on average it is still bending slightly away...

If this means the 12x could end up having a similar or even better lifetime (in excess of 500h?!?), there is no way to tell until this diode dies and it's full degradation pattern is known.



It would be quite unbelievable, if a 160mW CW diode could deliver near 600mW CW for that long. It would mean it could be used even for professional purposes, maybe not quite at 600mW but definitelly way over the power it is rated for. And that for our purposes it can be safe to go even further.

But it would also mean, that there is a bizzare difference between 12x diodes from the high and the low end of the efficiency spectrum. I definitelly wouldn't wanna see a low efficiency one again, as i wouldn't know what to do with it.



Unless something strange happens with the diode, I'll probably be posting combined updates for a while longer, as i have some urgent laser-work to finish. May be a bit slower on this end.

 

[daguin]

I noticed that my first 12X is finally starting to show some noticeable degradation. Originally it was putting out 620mW @ 425mA. Now it is at 600mW. I have not been keeping good records of it, but my estimate is ~30 hours of usage now.

I recharged the batteries and cleaned the optics again to be sure, but there was no difference.

So after ~30 hours, mine has degraded ~3%

Peace,
dave

 

[IgorT]

The diode safelly reached 100h @ 600mW! Here is a combined re-plot for 60, 80 and 100h.


Degradation @ 600mW initial Po (100h elapsed):

After 100h of 424mA degradation is becoming quite noticable by itself. The power dropped by almost 4% to 577mW (96.167% of initial).

I missed 100h by 2.7h, so the numbers actually apply to 102.7h, but the plot above is correct, since it extends just as far, it's just cut off at 100h for now.



Total degradation (120h elapsed):

Since the total time is 18h ahead of the 600mW time and the diode did an extra 2.7h i made this plot go to 120h.

Over all the steps so far the diode degraded to 92.967% of it's initial efficiency.

I am guessing it has at least another 7-8% more to go before it can die, which should take more than just another 100h, but it's possible it will degrade even further than that, since at lower powers degradation is not only slower but also drops further before a diode dies, compared to higher powers.


I believe that even after all the torture so far, this diode would still make a great laser, as it seems to have a lot more life left in it. Slightly sad i have to kill it, since that's what it was originally supposed to be, but i would really like to know what these are capable of...


On another note, i can still barelly believe this little diode is surviving the same currents i set open cans to but for longer! Especially considering that at almost double the voltage, the electrical power going into it is twice as high... At this moment the diode is at 7076 cycles and still doing fine.


I have a little more work to do, after that i'll also be able to test faster.

 

[daguin]

I just got one that has degraded 50%. Of course I have no way to know how it was actually handled, but the laser is not very old. It has all the familiar dark areas in it's output (although no "smiley face"). It was set originally for longer life at 500mW. It is now putting out a "messy" 250mW ! It still focuses and burns (like a 250mW laser), but the output has "holes" in it.

So 50% degradation and still lasing.

Peace,
dave

 

[yobresal]

50% degradation seems like a heck of a lot under normal or even extreme use. It is my belief that if you were to remove the window and clean the die of your laser it would put out close to 500mW again. Perhaps the diode just wasn't sealed properly or became unsealed in the harvesting process.

 

[Traveller]

I noticed that my first 12X is finally starting to show some noticeable degradation ... after ~30 hours, mine has degraded ~3%

The diode safelly reached 100h @ 600mW!
Over all the steps so far the diode degraded to 92.967% of it's initial efficiency ... I am guessing it has at least another 7-8% more to go before it can die...

I just got one that has degraded 50%. Of course I have no way to know how it was actually handled, but the laser is not very old ... It is now putting out a "messy" 250mW!

Due to all this 445nm excitement (my own included), I've lost track of the 12X saga. However, I've still considerable interest in the 12X 405s. The above posts however make me a bit reserved, considering these diodes are still a serious investment at this stage... .

Is there a general consensus forming here (yet)? Are 12x diodes the holy grail of bluray DIY lasers or is it just a more powerful - but less predictable (in terms of stability & longevity) version of the 8X?

 

[Exerd]

50% degradation seems like a heck of a lot under normal or even extreme use. It is my belief that if you were to remove the window and clean the die of your laser it would put out close to 500mW again. Perhaps the diode just wasn't sealed properly or became unsealed in the harvesting process.

I agree. I had one 12X that lost over 100mW due to buildup on the diode window. Quick alcohol window cleaning renewed it again.

 

[Traveller]

Is there a general consensus forming here (yet)? Are 12x diodes the holy grail of bluray DIY lasers or is it just a more powerful - but less predictable (in terms of stability & longevity) version of the 8X?

No one?

Say, Igor, what's your next move?

 

[Ref]

I agree. I had one 12X that lost over 100mW due to buildup on the diode window. Quick alcohol window cleaning renewed it again.

Ive never thought to try that. I notice what looks like dust splotches on the spill when not using a lens...maybe that will get rid of them. Rubbing alcohol and a q-tip?

 

[Exerd]

Sorry to state the obvious, but these diodes are something else!

100 hours and still over 96% is simply incredible. I'm not even close to 1 hour use on my primary blu-ray. This thing would last a few lifetimes at the rate I use it.

I would love to see what happens to these diodes at 700 and 800mW for degradation.

 

[IgorT]

A couple of weeks ago the body of a diode was discovered.
Dental records identified it as a 12x.
The autopsy revealed - it had been tortured to death.

The full autopsy report is attached below.



This is the final report for the 12x Murder Experiment (Take 3).
The third 12x diode died, but this time i don't have to feel (too) bad about it.

The diode survived almost exactly 263h since it's been set to 600mW or 281h from the very beginning!



Here's what happened from start to finish.

Degradation Rate Comparison:

This plot shows the full life of the 12x compared to the entire lives of the two tested 8x's.
Unfortunately the purpose of this plot was defeated early on by the burn-in effect, so there isn't much to comment here.

There is one thing tho, that became evident here. The 12x degraded almost to the same percentage as 8x #1, but it took it longer to do so. The degradation was slower at the start, but then it sped up, or rather slowed down less, than with the 8x's. In fact, except for the few bumps the plot could almost be linear for the 12x, however this doesn't show the whole picture...



Total Degradation:

This plot is an approximation of what would have happened, if the diode was set to 600mW from the start. The only difference is, it would have dropped further in the first 18 hours and the total time would have been a little shorter...

As can be seen from the plot, the diode degraded to 83.5% of it's initial Po in total during the 281 hours of torture…



Degradation in mW:

While the other plots show percentages of initial power, this one shows how much power was lost in mW. The last three hours are extrapolated, but it's probably safe to say that the power was very close to 520mW just before the bitter end.

The diode lost a whole 80mW since it's been set to 600mW!



PIV Comparison from Fresh to Dead:

I made this plot to show how big this difference actually is. The blue line is the diode when it was brand new, the pink is where the diode was just moments before its demise.

If i compare this to the five 12x PIV plots i recorded at the beginning, this diode went from being among the most efficient ones, almost down to where the lowest efficiency 12x was.


If you look at the five 12x plots at the beginning of this thread you will notice that 12x #3 was actually the third best in slope efficiency, but in terms of absolute efficiency, the top three diodes were identical. That's why i believe all three would have given pretty much the same results if tested.

Since this experiment also tragically confirmed that efficiency DOES indeed matter for diode toughness, this means that the results are very likelly the best case scenario for a 12x diode.


600mW appears to be quite "safe" for our needs (IF your diode is a high efficiency one!).
If you can live with less than 200h+ (and most of us can) you can actually go even further and get years of pointer use out of a (good) 12x.


At the same time, it's a little scary, just how much 12x can vary from one to another, so if you stumble upon a low efficiency diode don't be surprised if it can't even reach 600mW.

I do however think chances are good, that diodes like the second one tested are pretty rare.

 

[Traveller]

The diode survived almost exactly 263h since it's been set to 600mW or 281h from the very beginning! The diode lost a whole 80mW since it's been set to 600mW! ... the results are very likelly the best case scenario for a 12x diode ... 600mW appears to be quite "safe" for our needs (IF your diode is a high efficiency one!).

Welcome back...
Great finish to an epic project, thanks! Looking at FrancoRob's 12X table, it would seem that roughly 50% of the participants managed 600mW+ so your assumption appears to hold true. This also means that at least 50% are efficient diodes, no?

In any event, the 12X still holds the crown for the best [visible] burner in town... :beer:

 

[qumefox]

In any event, the 12X still holds the crown for the best [visible] burner in town... :beer:

Not sure how you figure that. 1W of 445 is going to heat stuff faster than 600mw of 405. 40nm isn't enough difference in wavelength for better material absorption of a smaller wavelength to overcome the 400mw higher power.

 

[jayrob]

I would say at close distance the 445 is going to burn better for sure...

But at farther distances, the 12X is better because it is a 'pin point' dot...