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

[mixedgas]

"Its time to make the music, its time to light the lights, its time to get things moving, on the laser design tonight"

Theme to the Muppet show, paraphrased.

Sorry Mr Henson, but I loved your show, and that theme song sticks in my head...

Big design post with drawings coming soon.

I had a sudden, urgent, issue at work, so I'm leaving late.
I wanted to leave at Noon.

Steve

[planters]

Had a thought. Jon and Krazer may both be right.

If vandate is birefringent, then the coefficient of absorption is polarization dependent (obviously). If the diodes in Jon's picks are polarized and orthogonal then if the vandate is oriented so that its favored absorption aligns with one of the diodes then the absorption depth of the other diode will be longer and so the summed 808 absorption will cause an initially large drop followed by a more gradual drop off due to the weaker absorption of the diode that is oriented 90 degrees to the favored polarization . Because this is radially symmetrical and the self absorption of the vandate at 1064nm is small then I am not sure that this matters. But,if it did then by rotating the vandate in the plane orthogonal to the pump beam there will be a point (actually 2 points) where the diodes are equally favored. Also, by placing the crystal close to the flat mirror in a semi-hemispherical resonator a longer absorption depth will have less effect on mode/pump diameter mismatch.

Also, the slick thing about a flat, 45 degree, 532 pass/1064 reflect, dichroic fold mirror is that it does not introduce any astigmatism itself.

[steve-o]

/ .. the 1w direct injected green diodes available for $50 which would be released the day I got it working

I keep thinking about that too.. it happened with the 638 red and the 445 blues. Wouldn't that be the shizz in the punchbowl .. oh the howwor .. Well, pushing on anyway just in case it doesn't happen ..

[planters]

I keep thinking about that too.. it happened with the 638 red and the 445 blues. Wouldn't that be the shizz in the punchbowl .. oh the howwor .. Well, pushing on anyway just in case it doesn't happen ..

This will almost certainly happen, and I think everyone has considered this. However, these are based on the GaN semiconductor that is used for the 445's and remember when the first A series appeared they were already 1W +. I think if they could have they would have because the display market is big and could use direct green immediately. So, I suspect that these will evolve rather than suddenly appear at a power level that is competitive. I would place that break even point at 500mW at less than $100 each. At those power levels they will almost certainly need to operate multi mode and the remarkably low divergence of the current, low power single mode devices will disappear and then all the issues of beam size/divergence will limit you to something on the order of a PBS quad. This leads me to think a 2W at a little under $1,000 all up would be about what that alternative would be. At that point(given the slow economy...2 years??) you might build your next green that way, but a functioning DPSS would still have value. With the color correction board I really don't notice a modulation disadvantage with the DPSS, but I suppose that would be one advantage of the direct diode.

[dsli_jon]

..because the display market is big... So, I suspect that these will evolve rather than suddenly appear at a power level that is competitive.

Indeed, but food-for-thought is that, by and large, (..save-for those amazing-little green-engines for the 'Pico-pj's.. those are beautiful little micro-greens, but a far-cry from multi-W...) direct-green dev'vers are likely going to 'favor' high-power / power-stability, and will care much-less about 'beam-quality', since the tv / cine-pj market is going for 'über-bright / efficient illumination-sources', vs beams... So, I'd expect the high-watt emitter-sizes to be rather fatt, and, as the 'Mitsu-red' gauntlet - and even the 2W blues, has-showed, in the end, you'll likely not end-up with a 1mm beam @ 0.5 mRad divergence so.. Trade-offs will most-certainly need to be 'settled-for'...

..How did that 70s lyric go, '..if ya can't be with the one you love, hunneh, love the one yer with..'

.02
j

[steve-o]

"hunneh" .. ROTFLMFAO !!

[steve-o]

This MCA from an ebay auction just came in the mail an hour ago.. Now just need a 4W 808 pump diode, figure out how to sandwich it w/ the indium foil and heatsinks, and get the right lens to pump it in the right direction .. and of course hook up the web cam to "view" the alignment. No looking at this puppy w/ bare eyeballs. Sure is a tiny thing. There's some part numbers on the case. This should be good for about half a watt of 532 ..




Found this page in a VLOC pdf catalog .. looks similar but the angle of the 2 crystals is different..



This is side pumped. Does anybody know where to focus the 808 spot on this thing?

Here's the ebay listing.. looks like he's still got more for sale (if anyone's interested) .. :

http://www.ebay.com/itm/500mw-532nm-...item19d687bb1a

[mixedgas]

It just so happens that Monday I need to "Surf" a Ti-Saph for a hour to keep it aligned and tuned. The experiment is not built yet, so I'm just free running it into a power meter. We run at 805, so tuning up to 808 is no problem.

It has AO modelocking, so if I turn off the RF its a cw laser.

I'll put a piece of Alpha cut vandate into the polarized 808 beam, and see what happens.

I can't see the adsorpton length, unless there is some florescense. but I can measure the 808 in vs 808 out at normal and extra-ordinary orientation.

That may help with the vandate polarization mystery.

Ultrafast lasers need to be run often to keep them aligned, so if I'm wasting photons I might as well use them for good cause.

Steve

[badger1666]

Hey steve-o
Not side pumped , just pumped on the yvo4 side , so just point the beam on the side with
Xtal on the outside , ie the one set at an angle ot the rest

This MCA from an ebay auction just came in the mail an hour ago.. Now just need a 4W 808 pump diode, figure out how to sandwich it w/ the indium foil and heatsinks, and get the right lens to pump it in the right direction .. and of course hook up the web cam to "view" the alignment. No looking at this puppy w/ bare eyeballs. Sure is a tiny thing. There's some part numbers on the case. This should be good for about half a watt of 532 ..







Found this page in a VLOC pdf catalog .. looks similar but the angle of the 2 crystals is different..



This is side pumped. Does anybody know where to focus the 808 spot on this thing?

Here's the ebay listing.. looks like he's still got more for sale (if anyone's interested) .. :

http://www.ebay.com/itm/500mw-532nm-...item19d687bb1a

[steve-o]

Thx Badger, yeh I kind of figured to pump the vanadate .. but where exactly , on any of the 4 flat surfaces (i think it may matter) and polarization etc ..
Steve, I'm not trying to derail this thread.. just adding info from another perspective .. may help .. may not .. too much info never hurts .. :]