Rhodamine 6g & 532nm

[planters]

The optimal Ref% of the OC should be related to the gain within the cavity. So, with an argon/jet vs. a cell/KTP there would likely be a different optimal %. Did the authors suggest in which direction the 5% OC was not optimal? Do we know what the existing LS dye head OC % is?
The degredation of the dye is suposed (acording to Exciton) to be inhibited by the presence of COT, but the mechanism was not explained and the value of the surfactant may not apply to all dyes, but probably could be emperically checked in each situation.
I remember the discussion about exchanging dye solution and that it is somewhat of a pain. Having done this before, the biggest issue was the dye and the components staining everything, but that if initially seting up a dye station for fluid mixing and with plenty of disposable layers and bins to hold waste I'm not too afraid of this. As I think one of the most interesting things with dye lasers is the investigation of different dyes, concentrations and additives I will be doing a lot of exchanges. Any additional hints or tricks especially as it applies to the LS head will be appreciated.

[mixedgas]

If we know the reflectance of the starting OC and can measure the single pass gain, we can calculate the optimal %T using the math in Silfvast's book.

I have a broad band dye OC for the red/yellow.

I kept a 375 ring dye. Once the new job starts I may be able to spend some time on this.

I can get the paper at the local uni library on the weekend. They still have it in hard copy, on a shelf, which is rare.

If I were making money doing shows I'd have no problem blowing 4 watts of 532 on 1 watt of 580, or is the 488 doing most of the pumping?

I have a spare jet and I know where a few of the jet pumps are laying outside rotting.

Steve

[mixedgas]

See attached, from the other thread.

Steve

[planters]

If we are talking about my plans then it will only be Q-switched 532 and converting the 532 pump into a high quality dye output is worth the conversion loss (just want to minimze it). I'm not making money doing shows, but investigating these broadly interesting questions is worth some money. My bigger problem is time.

[jonsinger]

I avoid methanol for several reasons.

1) Nasty toxicity. _Nasty_.

2) Isopropanol is available at any drugstore. May even be less expensive.

3) See that Russian article about improved performance with flashlamp pumping. Granted, they didn't test it against methanol; but iso was a clear win.

4) Methanol is probably even more flammable than isopropanol, but don't quote me on that -- I haven't actually tested it.

Cheers --
jon

[mixedgas]

Jon, did you get your optics in the mail?

Steve

[planters]

I'm not sure what the relative output performance of say RG6 will be in various alcohols. Now add in the addition of water and additives as well as different glass flow tubes. The numerous combinations seen in successful set ups means that it will probably take a few adjustments/substitutions to optimize any given real world dye head such as the Laserscope or the Coherent. But this should not be too hard. I'm kind of interested in using standardized (or nearly so ) dye heads pumped with relatively inexpensive lasers such as a KTP or ion to produce RGB for projectors. This is in contrast to the approach with diodes (been there) where the simplicity and light weight is countered by the lower energies and much worse beam characteristics. Flash lamp is also interesting. As a very bright, wavelength flexible, high beam quality source it might produce an interesting addition for say aerial displays especially if the low rep rate can be compensated by beam or pattern generation that does not depend on scanning; like something as simple as a diffraction grating. SELEM should be a lot of fun!

[jonsinger]

Flashlamp pumped dye lasers are fun. They tend to have rather low repetition rates, though, unless you have very good power supplies and switching and cooling. Still, at a basic level they are relatively easy to DIY, and they are very interesting to explore.

As to performance with various alcohols & solvents, my bet is that this is primarily an issue with flashlamp pumping, and that it should be fairly easy to decide -- if you find yourself mixing up dye solution too often, try a different alcohol and see whether it works better and/or lasts longer. With flashlamp pumping I've run R6G in water (with Ammonyx and with other detergents), Everclear [95% ethanol], 70% iso rubbing alcohol, and 91% iso. Possibly also in 99+% iso (available at electronics supply places), which I've definitely used with N2 laser pumping. I never kept tabs on output energy or solution lifetime, though, so I can't comment on it from personal experience.

I haven't done any CW dye yet, but will report on solvent if/when I do so. I won't be using EtGly, that's for damn sure. I value my health. (Not as nasty as methanol or MEK, but seriously not your friend. Also not your dog's friend, nor your cat's -- apparently some pets will investigate it and decide that they like the flavor, whereupon they get poisoned by it.) PropGly, maybe, if I can get my hands on enough of it.

It's probably clear that I'm at the low-power end of the thing. All of this talk about multiple watts of power out of secondary lasers pumped by monster primary lasers is astonishing to me... It's also confusing because of terminology I'm not familiar with. (I know what KTP is, but "LS"? "SR"?) It's also a bit of a shock for me when I see people put the word "inexpensive" in the same sentence as "KTP or ion". I'm in a whole different world, where even a $60 mirror is expensive and where a machine shop is something I probably won't have until Jim Newton & friends manage to open a TechShop in this area.

I'm also interested in DPCWDL (Diode-Pumped CW Dye Lasers), but again at low power. Once I get the CR-599 set up and aligned [many thanks to @mixedgas and @lesioq for parts help!], we'll see whether I can even bring it to threshold. I took a quick read through the alignment procedure yesterday, and it may not be easy to align the thing if it won't threshold; but we'll see about finessing that if necessary. (I've done lots of bizarro alignments, including, about 20 years back, a 50-mW HeNe head that's 7 feet long... my alignment laser wouldn't propagate all the way down and back without hitting the walls, so I had to think _very_ carefully about what I was seeing. Took me a day and a half, but I did get 51 mW out of the thing eventually, which is respectable for an aged-out tube. Alas, the tube is so ancient that the Brewsters are sealed on with epoxy, and I didn't realize that I needed to run it a lot to keep it clean. No more getters left, so it's fundamentally toast. Very little chance that I will have time to rebuild the tube, and there's no way I'm going to get a new one for it. Sigh.)

Back to the fray...

Cheers --
jon

[planters]

I agree with all of this. I can feel for you with that HeNe; many years ago tried to construct a CW argon out of a TIG welder and various... well you know. The toxicity thing doesn't concern me too much as the entire project space has so many hazards that you need to approach access, storage, disposal, ventilation as well as visual and electrical threats (god even vandalism) with some diligence.

If you have a well conceived need from time to time I may be able to help re. the machine shop thing.

I don't like the propylene glycol alternative as it has a higher viscosity when in combination with water especially at reduced temps.
The LS stands for Laserscope.
Don't get me wrong, my statement about cost is not a snob thing. It has to do with a $/Watt of USEABLE output. When you start to look at the total cost of accumulating all the bits to get a working multi-diode RGB projector running the cost of a surplus pump laser seems less intimidating. That $60 mirror IS expensive especially when it turns out that you have to reorder a slightly different mirror because you miss-estimated. Know what I mean?
On the CW front I've had the 445nm diodes up to 2.0A on a TEC with an O-like lens and 2.0 W output and they're stable.

[jonsinger]

I agree with all of this. I can feel for you with that HeNe; many years ago tried to construct a CW argon out of a TIG welder and various... well you know. The toxicity thing doesn't concern me too much as the entire project space has so many hazards that you need to approach access, storage, disposal, ventilation as well as visual and electrical threats (god even vandalism) with some diligence.

If you have a well conceived need from time to time I may be able to help re. the machine shop thing.

I don't like the propylene glycol alternative as it has a higher viscosity when in combination with water especially at reduced temps.
The LS stands for Laserscope.
Don't get me wrong, my statement about cost is not a snob thing. It has to do with a $/Watt of USEABLE output. When you start to look at the total cost of accumulating all the bits to get a working multi-diode RGB projector running the cost of a surplus pump laser seems less intimidating. That $60 mirror IS expensive especially when it turns out that you have to reorder a slightly different mirror because you miss-estimated. Know what I mean?
On the CW front I've had the 445nm diodes up to 2.0A on a TEC with an O-like lens and 2.0 W output and they're stable.

Hi.

A) CW argon seems like a really difficult project. My hat's off to you for even thinking about trying, much less actually trying.

B) I fully understand about hazards in the project space. I am fortunate enough to have a good chemical cabinet, but 35 kV is not exactly your friend. Sad about vandalism... argh. (I haven't had an issue with that, at least so far. Not too many randoms get in here. Fingers crossed in hopes that it stays that way.)

C) That's a very kind offer. So far I've been able to do just about everything with a drillpress and a Dremel (including a laser mirror mount -- http://www.jossresearch.org/pictures...mountX.10c.jpg -- pseudostereo macrophoto for cross-eyed viewing), but there are some limits. We'll see how it goes. Again, though, many thanks.

D) Very intriguing about PropGly; didn't know the viscosity was higher. Hadn't thought about possible differences in the temperature coefficient of viscosity, either... Hoping to avoid it, but may have a similar issue with other materials. Thanks for the heads-up; I will watch out for this!

E) Ahh. Laserscope. Okay.

F) Didn't think it was a snob thing; figured it was a "different worlds" thing -- I mostly get to deal in milliWatts, not in Watts. (Average power, that is; I'm working up toward 1 MW with the nitrogen lasers, but of course that's peak.) I know _exactly_ what you mean about having to redo something after mis-estimating it. It's all part of the deal, but it ain't comfy.

G) VERY good to know about stable 2W from a 445nm diode + a TEC. I am hoping not to need as much power as that, but of course there's this little focusing problem because the thing is multimode. (Did you know that Shuji Nakamura's new company seems to have [in the lab] 0.75W singlemode blue diodes now? At least, that's the report I saw somewhere.) I've been playing with an external mirror on my regular diode, but I haven't really tried to restrict the mode structure at powers much above threshold.

Cheers --
jon