"ML" 589nm

bloompyle · Jul 12, 2013

I got my 589nm PGL-III-C from the GB a couple days ago, and I was playing with a grating, and noticed something. Happened when the gal was over so I had her sanity check me... Yes. 3 dots. The extra 2 are both <589. One mostly yellow, and another greenish.

I told Raffle immediately as he's my go-to for dpss. He was baffled and did it too. Same thing. As he scratched his head, he said perhaps 585 and 546nm.

Seems a much yellower green to me, like 556 or higher. Though I'm no expert. I can post pictures in the morning, but my camera does a horrible job differentiating the "yellows".

Here's the kicker, they only stay for about 15sec before warmup, then all 589 after that.

Thoughts? Pics up after work tomorrow.

These gratings man...

Sigurthr · Jul 12, 2013

SFG uses an 808 pump for a crystal that lases at 1064nm and several other nearby lines deeper in the IR spectrum. The crystal that follows that does the actual SFG to combine the 1064nm and the other main IR line doesn't care what wavelength the other line(s) are. And that there is how this happens; the first crystal lases at 1064nm, your normal target wavelength (1342nm for 593.5nm), and sometimes during startup other additional lines. When the second crystal combines the 1064nm with the other additional lines you get additional wavelengths outputting. When the first crystal lases at only 1064nm you get only 532nm out, which was the common "warm up green" seen by early yellow pointers.

Trevor · Jul 12, 2013

Well, your 589 is doing SFG on 1064nm and 1319nm. 1064nm is fairly dominant, so I'd expect it would be a product of that and something else, but that's not necessarily guaranteed.

There's possibilities at 546nm, 551nm, and 571nm. 556nm and 561nm are also on the table.

But really... it's impossible to say unless you test it with a spectrometer or do really precise measurements with a diffration grating using the 589nm and a 532nm laser as references.

Trevor

ZRaffleticket · Jul 12, 2013

If it's also very similar to 589nm in color it might very possibly be 585nm due to a bad coating (or lack of transmission control within 12nm of 1064nm-- 1052nm may also be present)

Being 589nm is in a very "easily manipulated" eye color response area, a 4nm difference is likely a noticeable one.

As for green... probably 532nm

I did forget about 571.5nm being a possibility. Though I find that a bit less likely...

Edit: for anyone interested, I'm trying to reproduce the results with a prism. *puts 589 in freezer*

I only got the green to show so far

Edit 2: Man how'd you find this at all. At least for mine you'll only see the other line(s) for more than a few seconds coating this in a dry ice... I can't even get the green again

Trevor · Jul 12, 2013

ZRaffleticket said:
If it's also very similar to 589nm in color it might very possibly be 585nm due to a bad coating (or lack of transmission control within 12nm of 1064nm-- 1052nm may also be present)

Being 589nm is in a very "easily manipulated" eye color response area, a 4nm difference is likely a noticeable one.

As for green... probably 532nm

I did forget about 571.5nm being a possibility. Though I find that a bit less likely...

Edit: for anyone interested, I'm trying to reproduce the results with a prism. *puts 589 in freezer*

I only got the green to show so far

I can find reference to 1052nm emission in Cr:YAG lasers, but nothing from neodymium... am I missing something?

Trevor

ZRaffleticket · Jul 12, 2013

Sam's Laser FAQ - Solid State Lasers

Nd:YAG has over a dozen other weaker lasing transitions between 1,052 nm and 1,444 nm

http://en.wikipedia.org/wiki/Tunable_laser

Nd:YAG has weaker transitions at wavelengths of 1052 nm, 1074 nm, 1112 nm, 1319 nm, and a number of other lines.[6]

Didn't see that it was a weak line though. Might actually be 571.5nm then. Though letting 946nm into the mix... that's odd.
That still doesn't sound right though...

Edit: nevermind, wiki's wavelengths at least tell me common lines LPF knows about. 1052nm could SFG with 1319nm.

Wolfman29 · Jul 12, 2013

Very interesting. I'll have to check this out on mine when I get the time tomorrow.

Trevor · Jul 12, 2013

ZRaffleticket said:
Sam's Laser FAQ - Solid State Lasers

Didn't see that it was a weak line though. Might actually be 571.5nm then. Though letting 946nm into the mix... that's odd.

EDIT: Oop, you edited while I was posting the stuff below. Well, it lists 1319nm as a weak line too, and that's used in this laser to get 589nm. With that in mind, 1052nm seems pretty likely.

From the sound of that page on Sam's Laser FAQ, it seems like 1053nm only has relevant levels of gain in Nd:YLF, not Nd:YVO4?

And I agree... 946nm in the mix would be weird. But then again so is the behavior of the laser to begin with.

Trevor

ZRaffleticket · Jul 12, 2013

589nm uses Nd:YAG
593.5nm uses Nd:YVO4

Edit: Well... more commonly with 593.5nm at least

1052nm looks like it gains in Nd:YAG

OH CRAP I FORGOT MY 589 IN THE FREEZER

I'm not even seeing light :tinfoil:

Trevor · Jul 12, 2013

Evidently I've fallen behind the times while I've been writing code; for some reason I thought Nd:YAG still wasn't used in CW applications.

Hm... if 1052nm gain requires 1064nm being suppressed, that would explain why these lines only appear as the last initially warms up. As thermal conditions become more favorable for 1064nm and 1319nm to gain and result in 589nm, the 1052nm transition stops lasing.

...then there's still the question of the green. SHG of 1064nm sounds fairly likely... but that implies that 1064nm is dominant enough to yield 532nm, which would probably muscle out 1052nm emission?

This laser needs to be put on a spectrometer.

Trevor

ZRaffleticket · Jul 12, 2013

Any way we put this, that's what it boils down to.

I am getting some light now, I don't have any low powered 532's anymore but from what I remember, this is it.

It still might be a freak and somehow let 537nm if bloom says its not 532nm, in that case it's SHG'ing 1074nm (also likely within coating "color" tolerance)

Edit: if I stay up any later I'm gonna kill my 589nm. I'll do more investigating tomorrow when I can...

ARG · Jul 12, 2013

There's a few cheapish 1,000$ spectros on ebay right now for you folks interested

bloompyle · Jul 12, 2013

I am eventually getting a spectro.

It's way too yellow to be 532. I am sure of that, it's right next to the other yellow line. If the 585 is right next to the 589, then 532 wouldn't be nearly as close. It's about 10-15nm away from the 585.

I was just wanting to see pure yellow dots everywhere, and it looked cool to see all the beams. I told her she'd like it, showed her, and noticed it then. She wasn't nearly as excited

ZRaffleticket · Jul 12, 2013

Well mine's spitting 532nm out for sure

I can't get any other WL's though. If you think its within 15nm you're likely seeing 589nm, 585nm and 571.5nm.

This letting 946nm lase if that's the case... that still blows my mind

bloompyle · Jul 12, 2013

Wish I had a better camera to pick it up.

It's pretty awesome though. 3 line 589, I love getting unique lasers like this.

ZRaffleticket · Jul 12, 2013

You and your Multilines

I'm gonna post the picture you sent me in a sec--

"ML" 589nm

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