The Big Green Thread (I'm gonna regret posting this in the morning)

[mixedgas]

Indium foil is used for sealing under pressure because it has almost no elasticity, yet flows under moderate pressure.
It will "WET" very clean glass and crystal materials, allowing for vacuum grade seals.

Indium goes between the copper and the module because it allows for small scale "Stick slippage" as the different expansion rates kick in. Yet it still conducts heat like any other metal, just not on the scale of say copper or aluminum.

Its not magic, you still have to design for the correct thickness of Indium foil around the optic.


Steve

[mixedgas]

Wow, nice find Chad!!!! Kudos! What do you make of this Steve and other Gurus?
2 and 3 W
http://www.aliexpress.com/store/prod...622745018.html

PPLN is just in this case, another means of doubling. You still need to design a cavity with a long waist in the PPLN. You still need to heat the PPLN.

The conversion rate is good at 30%, if the spec is true. I still have issues with such a short doubler. As far as I am concerned, a longer interaction length is better to a point.

I have no lifetime data on PPLNs yet. At least not MgO ones.

No spec on the power density or interaction length, either.

Its a nice part, but where are the parts for the rest of the laser??? Always a gotcha with these folks.

BTW, its a 35$ part, if the pricing were more realistic. Those are made for tiny video projectors. Which means some place in China is a nice video projector using lasers. Probably fits in a tablet.

This is more realistic, but such a short cavity is not so great for us more serious users:

http://www.aliexpress.com/store/prod...622744447.html

Besides, you need to temperature tune those, yet not overdrive them. See the outliers on the data curve fitting at the 1 watt end? That is the crystal system saying "OUCH", I'm nearly overdriven. Which is why they sell the PPLN outside of the modules.

Some one will of couse buy a few, drive the snot out of them for a week, and claim I'm wrong, However I want a MTBF of 3000 hours, and greater then 2 watts per module.

Steve-O, the 158$ module may be what your seeking short term. Expect it to behave like a blue diode, beam wise.

I'm in this for lifetime, field repairable units, light feedback, and beam quality. If I do shows again, I'm doing it with Argon like beams, and corporate customers.

I work with Verdi, Mellennia, and Vanguards, So I'm spoiled. I know what I want can be done.

I'm willing to trade off size, and live with water to air cooling if need be.

I want my optics to be on real mounts, so if a crystal gets a burn, a coating goes grey, or I get internal cracks, I can move it over and re-use it like the big boys.

Example:

A Service Engineer was in the other day, and saved my employer a bundle simply by sliding the doubling crystal over. Did not retune the cavity, just slid the crystal over and retweaked its position on the power meter. The cavity is sealed except for the doubling module.
Then he started the auto-tune firmware. It just passed spec at 10 watts. That saved a Prof 5-7K in shipping the laser to the factory. Better yet, it saved a visiting Professor from wasting a 5 day trip. Thank you main board jumper #X and Mr Service Engineer !! We know it will need to go to the factory eventually, but another 500 hours is another 500 hours. Point is, that feature saved the mission.



BTW, The Famous Greytracking was mostly caused by self THG UV generation in the doubling crystals. Just learned that, working on this project.

One aspect of this, the lasers I use at work auto-tune their temperatures, on command. It takes 10-20 minutes for the software to tell the heaters what to do, and its worth it. It then goes back to that setting quickly at startup. I can do the same thing manually in about 40 minutes. Not saying the group developed laser needs software at ALL, but its worth considering. I can see the pump diode currents go way down when it finds the peak.



Steve

[planters]

What is killing me is the lack of a simple spec list for a functional head. Any progress on the "standard Asian" 3-4 W design? Finding a source for each of the components and even compromising a little based on educated guesses I believe will progress very quickly with so many interested in this project. Note your kinda interesting link above, but without a design nothing much is going to happen.

[mixedgas]

What is killing me is the lack of a simple spec list for a functional head. Any progress on the "standard Asian" 3-4 W design? Finding a source for each of the components and even compromising a little based on educated guesses I believe will progress very quickly with so many interested in this project. Note your kinda interesting link above, but without a design nothing much is going to happen.

Planters, I have emailed you some PDFs for educational use. I can't reproduce them here by law.

Neither can you, but we can cite them with proper quotation.

None of them are state of the art, but its a start.

Please confirm receiving 3 out of 3 emails from oscar sierra romeo @ ohio DOT something (break the phonetics)

Steve

[mixedgas]

And The PLers possibly get lucky:

http://www.photonlexicon.com/forums/...390#post245390

I dont want to flat out copy LQ's design. That is plain wrong....

Steve

[steve-o]

What is killing me is the lack of a simple spec list for a functional head.

Yeah, we need a BOM

[mixedgas]

The question is where to get pairs of consistant, well polarized, 8 watt pump diodes in a nice mount.
I know who would help us with a group buy, US made diodes, but most of you would probably bow out when you see the quote.
Usually they come in lower then the Asians.

From a Fiber Coupled End Pumped Asian design paper using KTP. Single ended pump.

Green Watts --- IR WATTS
0.5 --- 4.0
1.0 --- 5.5
2.0 --- 10.0
3.0 --- 13.0
3.5 --- 16.0

Please dont tell me the IR threshold is too high compared to a pointer. There is a reason for that, mainly the 15% green transmission output coupler. You need a high transmittance to extract green on the hot end of the scale.

Not the best conversion I've seen. LBO would increase that. These guys grew their own YV04, so no idea on their quality. Their input fiber was big and they took no steps to stablize the pump wavelegth. This was with a 3 mm KTP length, which is very short.

We're no where near the BOM stage. Planters needs to take a look at what I sent him. I'll be glad to publish a list of suggested papers soon. You can get a look at them on DeepDyve.com or similar So no one gets in trouble.

There are not enough surplus FAPS in the world for all of us.

Steve

[steve-o]

--post edited until I can read Steve's edit ///
---post deleted ----

[mixedgas]

Here's the deal. I work with this stuff for a living. Please don't post papers/plans/designs, or run with a design until I take a look at it. We're going to do this with peer review so we dont end up with lots of wasted money or blown parts.

Trust me, I do this for a living. Its really, really common to find a paper with huge errors or something critical left out.
Just because you see this cool layout diagram, does not mean it works. It may be hard to align, a spec is missing, someone mis-read a parts list, etc.
Or you end up with a laser with TEM 4,4 and a M^2 of something horrible, say 5. Editors often do not check laser papers very well, if at all.


Purchasing PDFs of scientific documents and then posting them here WILL get Spec/Admin in Trouble. PLEASE DO NOT DO THAT!

If 1000-1800$ worth of parts is too much for you, please don't cry. This is not going to be cheap. Some of us may get creative and do it for less. But it is a risky, expensive project.


Steve's Partial List so far:

Diode-Laser-Array Single-End-Pumped 5W Nd:YVO4/KTP Continuous-Wave Solid-State Green Laser
Liu Jun-hai, Wang Chang-qing, Lü Jun-hua, Li Guang-ming, Shao Zong-shu, Wang Ji-yang, Liu Yao-gang, Jiang Min-hua
Chinese Physics Letters (impact factor: 0.73). 08/2008; 16(7):508. DOI:10.1088/0256-307X/16/7/014

Diode-laser-array end-pumped intracavity frequency-doubled 3.6 W CW Nd:GdVO4rKTP green laser
Junhai Liu ) , Zongshu Shao, Huaijin Zhang, Xianlin Meng, Li Zhu, Jiyang Wang,
Yaogang Liu, Minhua Jiang
Optics Communications (impact factor: 1.49). 173:311-314. DOI:10.1016/S0030-4018(99)00594-5

[planters]

Steve,

You're a machine. Go you! Thanks for the references.