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

[planters]

Even if you don't have a firm plan yet how about some idea what is guiding your acquisitions? What have you constructed so far? Not to be critical and this may just be the impression I get from your post, but I would not continue to look for components like the diode stacks without a general plan. I know the risks... the "stuff" is fun to have and I am guilty of this all too often. Do you have a turn-key back up alternative if the project is delayed or simply isn't completed?

[als1980]

Totally understand where your coming from. I have no timeline so not to much of an issue. My main project is my CNC cutter, and that's doing fine. The lasers were more of an offshoot. Ive made some crazy stuff over the years. Got my first laser pointer when I was 14 and have been hooked since. That's way back when a bs laser pointer cost $200-300. And you choice of color was red, red or red. Ive built just about any kind of laser you can think of. Favorite was a 10w+ green. Flash lamp pumped, but very cool. The diode stacks are stated for the CNC, just cant decide between direct diode use, or ND based. Would like to do a fiber laser, but cant seem to find a ND doped fiber, just YB. Any advice? Is it worth the loss in output power to gain q-switch ability? Goal is marking and cutting up to 1/4" material. Stainless, alum, etc.. Ideally I would like to double or triple the output to 532 or 355nm, but not sure if its worth doing vs just using the 1400w at 808nm. Another issue is suitable mounts for crystals, diodes, etc... Any leads? The reason for the "ton of stuff" is I cant pass up a good deal. I buy stuff at 1/2 what others would call a great deal. If something pops up I cant resist. LOL.

[planters]

The reason for the "ton of stuff" is I cant pass up a good deal. I buy stuff at 1/2 what others would call a great deal. If something pops up I cant resist. LOL.

The first step is recognizing that you DO have a problem. If you're like me then that is also the last step.

With all that diode power, I would consider the slab or laterally pumped rod approach as opposed to trying to finesse a significant amount of 808 into a fiber or the small end of a YAG rod. I'm not super familiar with laser machining, but My Q-switched YAG slices a lot faster through metal (and etches glass) than when CW.

You jumped from 808 over the fundamental to SHG and THG, but in any case, one advantage of planning on Q-switching is these harmonics , if you go that way, will benefit from it.

1/4"?...oh boy. That is unlikely and if you're in a serious production environment (it doesn't sound like it) you don't want to be cobbling together a laser cutter. If this is for low productivity personal use I would leave the thick stuff >1mm for conventional tooling. You might PM macona. He has some very nice low power cutting lasers integrated onto an X/Y set up.

Good luck.

[mixedgas]

Apologies to Clement Clarke Moore,

Twas the night of New Years, when all through the house
Not a creature was stirring, not even a mouse.
The stockings were gone from the chimney with care,
No hopes that a PACKAGE FROM MACONA soon would be here

No children were nestled all snug in their beds,
No visions of sugar-plums danced in their heads.
And I in my cap, Had just settled my brains for a long winter’s Design Session

When out on the lawn there arose such a clatter,
I sprang from the bench to see what was the matter.
Away to the window I flew like a flash,
Tore open the shutters and threw up the sash.

The glare on the breast of the new-fallen snow
Gave the lustre of mid-day to objects below.
When, what to my wondering eyes should appear,
But a beat up Postal Truck and a tinny ring on the door bell.

With a little old driver, NOT lively and NOT quick,
I knew in a moment it must be a another Bill.
More rapid than eagles his mutters they came,
And he shouted and said something about the Ice,
I shall not repeat it for it would not be nice.

"Now KTP now, Indium now, Rollers and A Laser head....
On, Foam On, Bubblewarp on, Cardboard, and NO Blitzen!
To the top of the porch! to the top of the wall!
He dashed away! Dashed away! Spinning out and skidded
As he spead off to the Postal Office Party.

As 737 airplane wings that before the wild Hampshire hurricane fly,
When they meet with a freighter, mounted from the Oregan sky.
So down to the bench top the new indium rollers flew
With the box full of full of Toys, and a bottle of Diet Coke...

And then, in a twinkling, I heard on the bench
The silence of a properly packed pair of Ktp crystals
and perusing of each little core-pak showed they are dry and clean!

As I drew in my head, and was turning around,
The Postal guy muttered about Suffield's snow plowing again.
I could hear him miles down the road, sliding again!
By then I had opened, with more delight, Planter's pack of flat indium, no bends in sight.
Postal guy get's double overtime, and that will make things all right!

Happy New Years to all, and to all a Photonic Night.


Thanks Jerry, Thanks Eric, Its showtime.

Jerry, I'll call Alan at Spectra, we shall find out what a C8-134 ENG 001 Vandate Head with a Q-switch is....

Time to make the donuts, er build the laser.

Got the boxes.
Steve

[steve-o]

^^ LOL @ Steve and his Christmasy rhyme.
Sounds like a plan is coming together,
And right on time ..

[macona]

I am going to guess that translated to "I got the package"

It's 1.3u head, that is all I know. I got a couple more of the little chinese heads with the integral diodes so I dont really need that one, figured you would like to play with it.

[mixedgas]

Man, ordering good crystals is tough,

Started milling the crystal mounts today. Found the Vandate and KPT crystal widths to be all over the place. 4.01 and 4.03 and 4.06 mm along one side of my 5 mm long Casix 4x4 mm Vandate crystal.

A -.1 / +0.0 tolerance speced 8 mm by 8 mm by 11 mm long BBO crystal "MADE IN GERMANY" came out at 8.1 by 8.2 mm for work. We are not pleased to have to mill out a new holder. I'm not happy, I speced the tolerance for the order, myself. If SP easily hit 8.0 -.1 /+0.0--- there should be no reason others can not.

After trying this with a narrow carbide end mill, I am not happy in copper.

So I ordered a couple of precision metric end mills and am going to use the backlash to my advantage, in BRASS.
I'll take the cooling performance hit.

Steve

[planters]

Steve,
I am not going to attempt to teach you to suck eggs. My experience with copper has ALWAYS been unpleasant. Sometimes tolerable, but never fun. I have wrestled with this and come to the conclusion that the "copper thing" may be a little overblown.

Consider that the pumped central channel of the vanadate may run hundreds of degrees warmer than the surface of the lateral sides of a typical 3mm x3mm crystal. Does it really matter that the copper, aluminum, brass etc metal of the mount is @ 1,2 or 3 degrees warmer than the cooling fluid moving thru it or the air cooled heat sink below it? I'm sure it does not. The thermal conductivity of the crystal is two orders of magnitude lower than the copper. Who are we kidding?

Regarding the out of spec. I thought about your director and the "twisted crystal", not a British rock band. Relieving the corner of your milled channel and compensating for milling errors are going to be important even if we can obtain very precisely fabricated crystals and so what about doubling of even tripling the indium film and allowing its plasticity to compensate for run out. At a thermal conductivity of 80mK, it is still an order of magnitude better conducting than the crystal and very successful laser are built with 4mm x 4mm crystals. These "fatter crystals will have the same thermal resistance to the cooling of their inner 3mm x3mm core as produced by a 0.8 cm layer of indium on each side

[mixedgas]

What I'm trying to say is the parallelism of S1 and S2 are what are controlled on crystals. Dont expect any other surface to be well controlled, unless you pay extra. Lesson learned.

Steve

[tribble]

Was this C145/7 or another free machining copper? Or was this the nasty hard copper? If the latter, maybe try some of the C145 or C147.