UPDATED: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

[NKO29]

Re: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

Great info! Great to know there's no need to buy a g lens with the already expensive 9mm diodes

 

[djQUAN]

Re: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

Or no need to buy a 9mm diode for the expensive G9 lens. :shhh:

 

[NO4H99]

Re: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

LaserSam, did you ever hear from DTR?

 

[SKeeZ]

Re: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

Thanks again for the review! I have a G9 comin in the mail!

 

[Atomicrox]

Re: G9 vs. G2 vs. 3-Element vs. Acrylic - A study

Great post, +1!

Would you mind running the test on a 405nm as well? (S06J maybe)

 

[andrewb]

:bumpit:

Added new plots for ML101U29-25, S06J, PL450B, and ML501P73 diodes.

-Andy

 

[Down with Umbrella]

Wow. I like the flat lines of the S06J. They don't seem to drop off under high currents like the other diodes. Very interesting.

 

[Atomicrox]

Thanks for the new tests!
Any plans to try the new 520nm diodes?

 

[NKO29]

i can say that MY G9 on the 500mW mitsu diode gave me ~45% over the 3 element lens Thanks for the graphs, i think it's clear to see which lens comes out on top

 

[andrewb]

Yeah, it turns out the 500mW Mits P73 was a tricky diode to test, because it turns out it's VERY temperature sensitive. Way more than the other diodes. Even though I was using a large copper heatsink for the tests, the slightest warming or cooling would noticeably affect the measured output power. I was getting different results for the G9 if I measured it first (with the diode/sink completely cool), versus if I did it last, after all of the others.

Even though the heatsink wasn't even warm to the touch, the few degrees difference did seem to make an impact on the results, which probably explains the difference you're seeing (as the G9 curve is probably slightly on the low side). I was seeing over 1400mW with the G9 if my heatsink was slightly cool (just from sitting in a cold room), but I didn't use that data, as I felt it was a bit biased.

The better thing to do would be to use a TEC on the heatsink, to try to keep the diodes at a more stable temp for these tests, but I didn't have one handy, and I'm not trying to go nuts here. (I was more concerned with trying not to blow up diodes, as I already killed one S06J when I tried to push it to 700mA, and it popped.)

Regarding testing the new 90/120mW 520 diodes, I'll probably pick one up once DTR starts stocking them, so I'll add that data eventually.

-Andy

 

[Tmack]

I've found my mitsu 500 to be very sensitive too.. If I want a good reading, I make sure I get it on a cold start when the laser hasn't been run for hours.

I too just killed a SOJ6 405 rip

 

[andrewb]

Hey Tmack,

Sorry to hear about your S06J. Do you know what current it was at when it died? Mine was at about 670mA. (And it was ramped up to that gently, using a bench power supply, not hammered all at once.) I know there are a couple of build threads where people have gone beyond that, but I guess those guys just got lucky. I decided to stick to 600mA for my measurements.

I love how the sad emoticon is purple, like a 405. Lol.

-Andy

 

[Tmack]

Haha it is quite fitting in our situation. ==------

Mine was only set at 450ma. It was a slight miscalculation of the room I had between the pre-wired driver and the pill. So of course a short was the cause of death. Lol now my host spacial awareness is borderline ocd.
I was also using a high tension spring for the lens on my wicked laser pen with a m140 in it. Over time it was leaving tiny shaving of copper from it having too much pressure on the module. The trace amount of copper built up on the diode Window causing it to heat up and melt the Window. I got to watch the raw output of a melting diode. Been a frustrating couple of diodes.
Good news is the new m140 in the pen is performing better. It's giving me 1540mw at 1.25a while the old one wouldn't hit 1400mw even when freshly built.
Learned some valuable information so it's not all bad (I repeat that every time I see the diode graveyard)

 

[Teslanium]

:thinking: For single line laser use shouldn't single-element lenses always be better than any three-element lens, which are built for chromatic correction across a wide band? Why use or even consider a three element lens except for multiple wavelengths?

Thanks for the study - good info to know. +rep.

R.

 

[LarryDFW]

andrewb;

Very nice job of automating the testing the lenses & laser diodes.

Interesting that the G9 lens works so well on all the different frequency diodes.

I have some lenses that are specifically coated for Red LDs,

and outperformed the std G2 lenses that I used to distribute.

LarryDFW

 

[campbiscuit]

Thanks Andy
That's good information, and I'm impressed with your array of tools!

Is the G2 lens a focal lens or just a correction lens?

I'm building an laser etcher, and wanted to calculate spot size.
I need focal distance to finish the calculations.

Thanks again