589nm misbehaving - wrong wavelength!!

[Sta]

Hmmm - good point - so maybe the orange is closer to 605nm? Turns out there are two Nd:YAG lines that produce something close to that with SFG - 1319 (Used in 589 SFG with 1064nm - so we know that the Nd:YAG in there can lase on 1319 seeing as it's a 589nm laser) and 1123nm (commonly doubled to 561nm). SFG of those two IR lines would produce ~607nm which would be a rather nice orange.

I wish it were 607nm!! But again, 589 to 607 would have made a much bigger 'jump' than observed. I think at this point it's pretty clear that it's going from 589 to 593.5... the question is, how?!

I skipped over the video stuff since video won't play on the terminal server I'm using at the moment. I should have at least read the description - sorry about that.

Yeah, if the spacing suddenly jumps and no other colors show up in any appreciable amount, that kind of has to be a yellow shifting to another yellow. I've got a spectrometer if you ever feel like getting this metered.

That's a very nice offer, Cyp, but I'm not comfortable mailing this laser anywhere. On the off chance that it gets seized, it would be horrific.

 

[diachi]

I wish it were 607nm!! But again, 589 to 607 would have made a much bigger 'jump' than observed. I think at this point it's pretty clear that it's going from 589 to 593.5... the question is, how?!

Fair point ... The only way that I can think of would be for the 1319nm line to die and for the 1342nm to immediately start lasing when 1319nm dies out... But Nd:YAG doesn't (or at least shouldn't) have enough gain at 1342nm and Vanadate doesn't have enough gain at 1319nm - as Cyp already mentioned. (I stand corrected on my earlier post btw!). I'd still imagine it's doing SFG but of something other than 1319nm an 1064nm.

Without knowing what wavelengths it's lasing at it's really hard to come up with more possibilities...

 

[Sta]

Fair point ... The only way that I can think of would be for the 1319nm line to die and for the 1342nm to immediately start lasing when 1319nm dies out... But Nd:YAG doesn't (or at least shouldn't) have enough gain at 1342nm and Vanadate doesn't have enough gain at 1319nm - as Cyp already mentioned.

Without knowing what wavelengths it's lasing at it's really hard to come up with more possibilities...

I just checked three different wavelength to RGB converters and 607nm looks almost exactly like the actual color. This is very strange, as it contradicts what the grating showed.

 

[diachi]

I just checked three different wavelength to RGB converters and 607nm looks almost exactly like the actual color. This is very strange, as it contradicts what the grating showed.

It's not a huge jump from 589nm to 607nm - Only 18nm - depending on the grating you might not see a particularly large change in position. For a diffraction grating with 300 grooves/mm you'd see a difference of ~0.4 degrees on the first order diffracted image if I'm calculating that right.

So back to my 607nm SFG idea?

Cyp - you should send Sta your spectro so that we can figure this out!

 

[Sta]

It's not a huge jump from 589nm to 607nm - Only 18nm - depending on the grating you might not see a particularly large change in position. For a diffraction grating with 300 grooves/mm you'd see a difference of ~0.4 degrees on the first order diffracted image if I'm calculating that right.

I just tested out a similar difference in wavelength - 520 to 532 - and it seems to have a much greater difference in angle than the yellow did. So it's probably not 607nm.

Edit: Perhaps someone can loan me a spectrometer...

 

[diachi]

I just tested out a similar difference in wavelength - 520 to 532 - and it seems to have a much greater difference in angle than the yellow did. So it's probably not 607nm.

Edit: Perhaps someone can loan me a spectrometer...

Were the beams at the same angle relative to the grating?

Bloody strange either way...

 

[Sta]

Were the beams at the same angle relative to the grating?

Yes, they were. I had the lasers stacked vertically and aimed such that the center dot would be in the same location. :beer:

 

[diachi]

Yes, they were. I had the lasers stacked vertically and aimed such that the center dot would be in the same location. :beer:

Just checking! :beer:

Got a university with a physics lab near you? They may test it for you if they have a spectrometer.

 

[Sta]

Just checking! :beer:

Got a university with a physics lab near you? They may test it for you if they have a spectrometer.

I was thinking the same thing, but I'd rather not walk into a university and pull out a cylindrical piece of metal... people are easily scared nowadays, they may think it is a gun barrel!

 

[diachi]

I was thinking the same thing, but I'd rather not walk into a university and pull out a cylindrical piece of metal... people are easily scared nowadays, they may think it is a gun barrel!

Call or e-mail ahead - professors and such should have contact details listed on the website. Failing that call reception and ask for someone in the Physics dept.

 

[Sta]

Call or e-mail ahead - professors and such should have contact details listed on the website. Failing that call reception and ask for someone in the Physics dept.

I'm still not quite sure this is a good idea; if this laser ends up being a different color than my 593.5nm pointer, then I'll consider my options. At this point I'm pretty much convinced it's 593.5 anyways. :beer:

 

[Cyparagon]

Cyp - you should send Sta your spectro so that we can figure this out!

Good idea... except it needs a laptop with a COM port, software, and would possibly be knocked out of alignment in shipping :undecided:

 

[ultimatekaiser]

Yes. The coatings have a reflectivity curve, and anything that falls into that curve and has enough gain can oscillate. The cavity length and stability are good, and the gains overcome the losses, it can oscillate. There are a lot of YAG lines that can mix to wind up with lots of colors. I've had several yellows and they All behave differently. And one of mine has a more exotic crystal in it that allows it to do 4 yellows at once, though only one is just barely. So essentially just three. I've been preparing a post for it, so look out for it. Yours might have one of the newer crystals or a fluke coating which is causing one of these other lines to oscillate and as the temperature and cavity length change, it's hopping between them as they fight for gain. The nominal wavelength of these is 588.6, but I've seen a few do other wavelengths near this, and I even have seen a new crystal that can do 584nm, and works in much the same way as the orange 607 process. Science is finally going after the oranges and yellows hard it seems. If you like I can offer to spectrometer your laser and tell you what is happening. Most laser mirrors are fairly narrow band but if it's within a few nanometers and conditions are right, It's not unreasonable for another nearby line to oscillate no matter how briefly. I have a HeNe that can lase basically all of the lines at once- green, yellow, both oranges, and 5 or 6 reds all at once! (Never checked for the IR ones)

 

[Sta]

Yes. The coatings have a reflectivity curve, and anything that falls into that curve and has enough gain can oscillate. The cavity length and stability are good, and the gains overcome the losses, it can oscillate. There are a lot of YAG lines that can mix to wind up with lots of colors. I've had several yellows and they All behave differently. And one of mine has a more exotic crystal in it that allows it to do 4 yellows at once, though only one is just barely. So essentially just three. I've been preparing a post for it, so look out for it. Yours might have one of the newer crystals or a fluke coating which is causing one of these other lines to oscillate and as the temperature and cavity length change, it's hopping between them as they fight for gain. The nominal wavelength of these is 588.6, but I've seen a few do other wavelengths near this, and I even have seen a new crystal that can do 584nm, and works in much the same way as the orange 607 process. Science is finally going after the oranges and yellows hard it seems. If you like I can offer to spectrometer your laser and tell you what is happening. Most laser mirrors are fairly narrow band but if it's within a few nanometers and conditions are right, It's not unreasonable for another nearby line to oscillate no matter how briefly. I have a HeNe that can lase basically all of the lines at once- green, yellow, both oranges, and 5 or 6 reds all at once! (Never checked for the IR ones)

Great, thank you Kaiser.
Do you have any idea what's causing the abnormally high power?
And I wish I could send my laser to you to spectro, but I can't risk it being seized. :beer:

 

[Encap]

I'm still not quite sure this is a good idea; if this laser ends up being a different color than my 593.5nm pointer, then I'll consider my options. At this point I'm pretty much convinced it's 593.5 anyways. :beer:

There were several cases a while back where members bought a 589nm and received a 593.5nm actually---will be interesting to see what yours is actually doing.

 

[ultimatekaiser]

It won't if you live in the states. (says you're in NJ. And even then there's ways around that. And power is dependent on lots of things.

edit: I doubt its 593.5. it could be, but creating that off a yittrium garnet (YAG) is quite difficult...usually they use an orthovanadate (YVO4) or yttrium Perovskite (YAP) to generate 1340/1342nm. That line is pretty weak in the YAG crystal structure, but it depends entirely on how the mirror coatings have turned out if they were fluked and drifted one way or the other due to the way they were produced its not impossible for it to be switching to 593 while cold and the 1342 line is stronger, then as it warms it favors the 1319 line. I tend to find the 589s tend to be hit and miss on the optics, as there are so many lines packed into that tiny area of the spectrum that can be created. one of my 593s has such overly high gain it also still weakly lases (leaks) light in the red and green with it in super tiny amounts.