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

[mixedgas]

The Vandate crystal axis determines the polarization, not the pump in this case. Good qustion though, and it is a issue in materials that do not self-polarize.

Steve

[mixedgas]

Steve-O, that lets us see a direction for 1 watt and down. Thanks for finding that.

Mickey, thanks for finding that on the wayback machine.
The 50$ a head scheme poses various problems for some of us in the US who are helping with this.

Steve

[mixedgas]

Also worth a read good conversion eff 42% eek
One of you gurus might make sense of it ?

End Quote.

http://www.col.org.cn/viewFull.aspx?id=COL02010029

Notice they skirt arount the output beam characteristics.

Or this http://lib.semi.ac.cn:8080/tsh/dzzy/...7/5737-109.pdf

Great set of drawings, nice data, but a MOPVE growth process is not something you can do in the back yard. They grew their own OPSL type crystal.

Wait til Sunday guys when I can post some drawings... All will become clear.

Steve

[mixedgas]

Quote:
Looking at the idea of side pumping would 2 pumps from opposite sides double the power without the need for more complex optics and associated alignment issues? Would this affect polarisation?
END Quote:

Just about everyone has went to end pumping for low powered stuff such as we seek.

Steve

[planters]

The 50$ a head scheme poses various problems for some of us in the US who are helping with this.

I don't think this will be a problem as long as there are going to be some serious contributors. Contributions that are broad as well as deep will work as long as the relatively small/head contributors don't establish a generalized expectation.


Badger,

The thin disks are where all the high power manufacturing is going and it would be neat to avoid thermal lensing. I just don't know if there is a source for these at reasonable prices or enough of a body of knowledge compared to the rod style. Steve, I hate to do this, but that's right, right? Too Never land and too distracting?

[mixedgas]

I was afraid I'd have to post this, so I might as well get it over with now.

My objection to the 50$ stuff is that lawyers may see this as a commercial enterprise.

Same objection to massive posting of patents in the thread or posting pictures of commercial lasers.
By posting a patent, you imply its validity. The Kuizenga patent I posted has already been tested in court.
Everyone knows about V-folds, that technique is "Known in the Art"

If someone starts selling the "PL" kit or design on the web, thats a issue.

We also possibly place Spec in a position of possible liability if a commercial design is copied and sold in any quanity.

Please wait until I do this the proper way with pen and paper.

Understand this, I will help individuals design a nice unit for themselves.

I need a few watts of green for personal purposes.

If I'm designing a production laser, then I need to profit from that enterprise and clear the legal hurdles.

I have no intention of entering manufacturing at this point.

So when I post the drawings, it will be "Build a few for personal use, production rights reserved"

I just talked to Spec, and he is worried about liability in the US from "Aiding and Abeting".

This is why I'm working from published research and textbooks, not copying willy nilly from patents, or existing hardware.
That is the correct way of doing things.

Everytime you guys post another patent, thats one less technqiue for me to work from.

"I'm gonna regret posting this in the morning"


Steve

[mixedgas]

Optically contacted thin disk in our case is too expensive. What we can do is use sapphire disks for cooling commercial MCAs in a lower power laser.

Steve

[Meatball]

Is there any idea at this point, of how many temperature controlled elements the set up will most likely have?

I'd like to start looking at some oven/cooler circuits, but I don't know if we are looking to thermally compensate for thermal lensing, or if that will be dealt with optically in the cavity via OC FLs and whatnot.

Using vanadate, I think we've eliminated temp control for the diode - just using water blocks instead?

The vanadate - circuit for direct control over thermal lensing? No need?

Doubler (I'm assuming KTP) - I think someone expressed favor for an oven, probably means it should be kept off the water block...

We can definitely keep things around the cavity solid state until heat is moved away from the resonator.

I've got a bit of time to spend on this as soon as the last week of this month starts up. Thanksgiving break will mean classes are basically over.

Don't make us wait till Sunday Steve, just pick up a napkin! All the greatest ideas were scrawled onto a napkin with an orange crayon at first... or sumpthin.

.. so, we can basically do whatever we want only after the first napkin drawings are made?

[mixedgas]

Quoting Meatball....


Using vanadate, I think we've eliminated temp control for the diode - just using water blocks instead?

The vanadate - circuit for direct control over thermal lensing? No need?


Vandate has a acceptance range of 20 nanometers, so one possibly weak TE loop for the diodes.

Spec is my laser must operate in Ohio ---> Cold, and Arizona Warehouse Parties----> Very Hot, 101' F

The lab lasers I've used (both companies) spec the pump diode heatsinks at a just chilled 18'C (which is 64F) and use weak TECs to steer things. We provide(d) chilled water to meet the spec. So call me maybe on the pump diodes, I hope not. I'm sure I can just relent and use water if I need it. The person who was here before me never refilled the refridgerant, and the lasers still ran well for 40 minutes til TEC overtemp.

Overclocking folks must have similar heat-loads, and they have these low cost water cooling add-ons.

Research those add-ons, Dr Meatball...

We can keep the doubler block off the water block using air or foam. You mount it on stiff pins of a low conductivity material like hobby shop 306SS rod.

Doubler (I'm assuming KTP) - I think someone expressed favor for an oven, probably means it should be kept off the water block...


LBO is looking better then KTP and Price is only 2X as much. You can drop in ktp into a LBO setup, but probably not the other way around. So One oven for the KTP.

I've got one paper "baking" the vandate to get rid of thermal issues.

Pump diodes maybe
KTP/LBO is ovenized
Vandate, cooled.

I work in a paperless operation ... Whats is a napkin? Snort....

I'm getting there, one more document to find some place, on the ratio of 808 diameter in the vandate to 1064/532 diameter, something about designing for 1064 set to 91% of 808 for best beam quality

After watching/helping a professional "neighbor" struggling to get a new pump laser beam matched to a old load laser, I'm watching the pump diameter issue closely.

When I dont have this hour commute, life will be easier.

PS, The next person who PMs me with a Apology will be slapped with a LARGE quantum teleported wet trout. Life is Hard Enough without worndering if I'm a jerk. Just watch the patent posts, and I'm sorry I started that. LOL....

I've gotten more then one, from more then one person...

Enjoy:

http://www.youtube.com/watch?v=IhJQp-q1Y1s


Steve

[planters]

I'd like to start looking at some oven/cooler circuits, but I don't know if we are looking to thermally compensate for thermal lensing,

It's my understanding that thermal lensing will not be compensated by cooling (near room temperature) because it is caused by the thermal gradients that are set up between the rod axis (where the high intensity beam passes) and the cooler outer diameter of the rod where it looses heat to its environment. The gradient will persist even if both the axis and the periphery run at a lower temperature. That is the attraction of disc lasers because the very thin gain medium prevents large thermal gradients from developing and what gradients remain are parallel to the beam and so produce little lensing. There has also been some work by a company ( you can look them up on YouTube) that is operating DPSS lasers at LN2 temperatures and seeing amazing improvements in beam quality and conversion efficiency. At these extremely low temperatures the gap between the absorption (pump) wavelength and the gain wavelength narrows, the delta refraction with delta T becomes smaller and the thermal conductivity increases by about an order of magnitude.

The cooling/heating of each component will depend, obviously on the design that emerges, but I think that it might be a benefit to plan on three separate and adjustable temperature loops. One loop for the diode, one for the Vandate and one for the doubler. If they are based on separate TECs that rest on a common water cooled heat sink then each can be experimentally optimized up or even down. If a loop is determined to be unnecessary then eliminate it when planning the next build.