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3x 445nm LD PIV Plot

IgorT

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I heard there was a lack of PIV plots for these new diodes...
As it happens, i just made a triple plot yesterday.

EDIT: The diodes came from an A130 projector, if it makes any difference at all....


This was actually the first time i had to switch my faithfull OmniDrive Diode Analyzer (TM) into the high current range (2A as opposed to 700mA in the low range) :evil:
A pic of the Diode Analyzer is in the third attachment for those who haven't seen it yet (heard there's a lot of new members)...


I set the Imax to 1.2A and plotted in 100mA resolution. It's actually a higher resolution than 40mA for an 8x or a 12x diode, relativelly speaking.
It would still show if there were any kinks and a higher resolution was required...
The reason i decided to limit the max current to 1.2A is that the Nichia datasheet that is suspected to belong to this diode model only in a different can, mentions 1.2A as the absolute maximum current, and i didn't want to cause any damage to them (prematurelly).


Here's what the diodes look like when plotted using a 405-G-1 broadband lens:




Two diodes (#01 & #03 had almost identical slope efficiency as you can see from the overlapping curves..

I only used one Vf curve so as not to make the graph confusing - it's about at the average Vf i found....


One thing that became immediatelly apparent was that they don't form straight lines like 405nm diodes do. The slope starts slower, then it "speeds up" somewhat, until at a certain point the efficiency starts dropping off, probably from the diode's sensitivity to heat (similar effect as with reds, only less pronounced)...


Except for the slight curvature changes in the plots there were no kinks anywhere and the diodes took the testing quite nicelly.


It is probably safe to say that the majority of these 445nm diodes will fall into approximately the same range displayed here, unless you stumble on a freak or a weakling, so this triple plot should give you an approximate idea of what power to expect at different currents....




I also wanted to take this opportunity to show off my first 445nm laser. :whistle:




It's in this wicked little stainless steel AA host wearing a 405-G-1 broadband coated lens...

I know most are being made in 18650 hosts but the build here is no crueler (to the battery) than making a keychain 8x laser (which a couple of members did)... Heat is apparently not a problem for it but i'll try in an aluminum host of the same model to see if there is any difference in power stability...

The beast delivers 1190 mW from 1A of current when cold! :evil:
And it's awesome, as those of you who already have a 445nm laser know...



P.S. Many thanks to Jayrob, who keeps making prototype heatsinks for me, regardless of how badly i annoy him with the details... :angel:
 

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Asherz

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Nice write up, lots of useful info.

That laser has one nice host, looks great :) veery nice build!
 

Meatball

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Igor! You're the man! Thanks for sharing your plots with us! Now I'll bet I can get 2W from my knife edge kit after corrective optics. :evil:
 

Gryphon

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Awesome graph! Are you going to be testing any of these diodes all the way till they fail?
 

cd520

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Nice work with the plot. Are these a130 or a140's?
 

IgorT

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Awesome graph! Are you going to be testing any of these diodes all the way till they fail?
Possibly, if time and finances allow... But once i do, i'll have enough data to create a lifetime approximation curve, like i did with the 8x's but was unable to repeat with 12x's as only one played along...


Nice work with the plot. Are these a130 or a140's?
Umm to be honest, i had no idea there were two types... :yabbem:
All i know is that they come from a Cassio projector. Does a1x0 refer to the model of the projector?

Is there any indication they are different from one another?
 
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RA_pierce

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Is there any indication they are different from one another?
I think the consensus is, "We don't know (yet)."
Most think that there is no difference and that the A140 projector uses "binned" diodes of higher efficiency for more light output.

Welcome back.

Edit: And that is a sweet build. Nice job. :D
 

IgorT

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Woo thanks Igor~!!! Hope your hand gets better!
My hand's been fine for a long time now, and actually it was just a minor nuisance in comparison to the main reason i was away for so long.

But the gory details are too personal for me to discuss in public, so let's just leave it at that...
 
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lasersbee

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Does a1x0 refer to the model of the projector?

Is there any indication they are different from one another?
Yes... The XJ-A130 is the Casio 2000 Lumen Projector... where the
XJ-A140 is the Casio 2500 Lumen Projector..

BTW... thanks for the Graph.... I would also like to know which
model of projector that your LDs came from...

I tested one of each and there were differences that I saw..


Jerry
 
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Meatball

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Possibly, if time and finances allow... But once i do, i'll have enough data to create a lifetime approximation curve, like i did with the 8x's but was unable to repeat with 12x's as only one played along...




Umm to be honest, i had no idea there were two types... :yabbem:
All i know is that they come from a Cassio projector. Does a1x0 refer to the model of the projector?

Is there any indication they are different from one another?
Dave sent you those diodes, didn't he? Theres a good chance that those will be the a140s... not that there is a known difference.. :whistle:

The a130 projector was not rated as bright as the a140 projector. So naturally, there was speculation about the diodes used.
 

IgorT

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Igor! You're the man! Thanks for sharing your plots with us! Now I'll bet I can get 2W from my knife edge kit after corrective optics. :evil:
Thanks! :yh:

What's a knife edge kit? Something you designed or something available on the forum?


I heard of a kit DrLava had planned, and it mentions TECs.
I do believe these diodes would benefit from a constant temperature setup...
That beginning of a "knee" at higher powers could very well be from the heat, so a constant temperature TEC rig might be able to straighten the line quite a bit = more powah at same current.

405nm diodes are not nearly as sensitive to heat, so there is barelly any difference in the results if you apply such a rig. Red diodes on the other hand would benefit from it the most...
 
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ElektroFreak

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Thanks! :yh:

What's a knife edge kit? Something you designed or something available on the forum?
Welcome back Igor!

Knife-edging is a way of combining two or more laser beams without the need for polarization. Basically, it boils down passing a beam just next to the edge of an angle mirror, and bouncing a second beam off the mirror, also just at the edge that the first beam passes by resulting in two parallel beams that are so close together that they can be seen as "combined". This method is how some major laser manufacturers can combine up to 20 or more diodes to make multi-watt arrays. The final output is always multimode by definition, but the fact that polarization is of no concern makes it attractive for combining many laser beams rather than just being able to combine two, like PBS cubes can.

Example of a knife-edged array:

 

Meatball

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This is the kit laserman532 made for me.

Laserman532 445 Dual Knife Edge Beam Combiner KIT

You think I can get 2W+?

I'll bet I can. My driver is set for 1.25A max for each diode..

I'm going to use Dr Lavas cylindrical lens kit to fix divergence, and after the expected 3% losses, your graph is telling me I might get something as high as 2.5W! Your results seem to be very consistent with lots of others' results!
 




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