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-   -   589nm misbehaving - wrong wavelength!! (http://laserpointerforums.com/f40/589nm-misbehaving-wrong-wavelength-97952.html)

Sta 07-07-2016 09:57 PM

589nm misbehaving - wrong wavelength!!
 
Hello folks!
Ever since I got my Spartan 589nm I felt that it was a little more orange than descriptions (and photos) of 589nm would indicate.
Sometimes when I did a cold start, it'd look yellow, I'd look away for a moment, and then it would look orange again.
Of course, it has to be just one of the oddities of color perception, right?

NOPE!

I was doing a test today to see if my Spartan put out more power when cold, like most 589s do, by placing it over an air conditioning vent for a few minutes, then turning it on.
When I turned it on, I could have sworn it was much more yellow than when I put it on the AC vent. But I looked away for a moment, and it was orange again. Must have been imaginary.
So I placed it on the AC vent a few more times, and eventually I realized I probably wasn't imagining things.
Then I set up my Dragon Lasers diffraction grating, and... :wtf:



You can clearly see that at 0:13, all of the dots shift away from the center, while the color becomes noticeably more orange.
This can only mean one of two things:
(a) The laser's wavelength is shifting significantly (potentially to 593.5nm),
or (b) I am an idiot.

Assuming (a) is true, WHY?! :confused:
Adding to the mystery is the fact that this laser peaks at 162mW (!!!) which would already be the most powerful 589nm handheld owned by anyone on this forum. But for 593.5nm, it seems totally ludicrous.
None of this makes any sense whatsoever. This should not be possible!

This is an incredibly confusing mystery, and I WANT ANSWERS!

If you've got any ideas for what's going on, why it's going on, or why (b) is true, please do post a comment. :)



Edit: 600th post, yay

diachi 07-07-2016 10:27 PM

Re: 589nm misbehaving - wrong wavelength!!
 
My only guess is that the temperature change is somehow changing the gain of the 1319 and 1342nm lines - the 1319nm possibly prefers it hot, thus you get 589nm once it heats up a little and the 1342nm likes it cold so you end up with 593nm when cold. I'd be interested in seeing a video of a spectro readout and a simultaneous power reading to confirm - although I know you don't have that equipment. Both 589nm and 593nm are produced using SFG, and the wavelengths are close enough that both might just work on the same optics under the right circumstances.

That's my guess anyway.

Sta 07-07-2016 10:45 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by diachi (Post 1431576)
My only guess is that the temperature change is somehow changing the gain of the 1319 and 1342nm lines - the 1319nm possibly prefers it hot, thus you get 589nm once it heats up a little and the 1342nm likes it cold so you end up with 593nm when cold. I'd be interested in seeing a video of a spectro readout and a simultaneous power reading to confirm - although I know you don't have that equipment. Both 589nm and 593nm are produced using SFG, and the wavelengths are close enough that both might just work on the same optics under the right circumstances.

That's my guess anyway.

But if 1319nm likes it hot then we should be getting 589nm under normal conditions. It seems to only be putting out 589nm when it's chilled - at room temperature it almost always outputs 593.5nm. But even if you're right, how could it be doing 162mW? That's unheard of for 593.5. Isn't the process far less efficient than 589nm?

Edit: How the heck should I mark this laser in my signature? :undecided:

Hap 07-07-2016 10:54 PM

Re: 589nm misbehaving - wrong wavelength!!
 
What needs to be addressed is how his Spartan could even be outputting 593.5? From what I've read DPSS lasers NEVER change wavelengths. I don't think it's outputting 163mW of 593.5, that power is only available in lab formats and having that much power in a pen would easily overheat it.

Curious as to what the findings are :)

-Alex

diachi 07-07-2016 11:00 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by Sta (Post 1431579)
But if 1319nm likes it hot then we should be getting 589nm under normal conditions. It seems to only be putting out 589nm when it's chilled - at room temperature it almost always outputs 593.5nm. But even if you're right, how could it be doing 162mW? That's unheard of for 593.5. Isn't the process far less efficient than 589nm?

Edit: How the heck should I mark this laser in my signature? :undecided:

May have got the temperatures the wrong way around... Got 5 thoughts going on at once here and more browser tabs open than I know what to do with. :beer:

Quote:

Originally Posted by Hap (Post 1431580)
What needs to be addressed is how his Spartan could even be outputting 593.5? From what I've read DPSS lasers NEVER change wavelengths. I don't think it's outputting 163mW of 593.5, that power is only available in lab formats and having that much power in a pen would easily overheat it.

Curious as to what the findings are :)

-Alex

Well that's not entirely true. My thinking is that it's producing a mix of 589 and 593 (or 1342 and 1319 I guess...) - when the temperature changes the lines gradually fade out/fade in resulting in a smooth transition between 593nm and 589nm (both there simultaneously) as one line gets stronger and the other gets weaker.

I don't think it's doing 163mW of 593 either - that's why I said I'd like to see it spectro'd and metered at the same time. :p

Certainly something interesting going on anyway.

Cyparagon 07-07-2016 11:03 PM

Re: 589nm misbehaving - wrong wavelength!!
 
I've never heard of a yellow randomly switching to another yellow. Coatings don't usually allow this, and I think the two different longer IR lines for each yellow only have sufficient gain in a different medium (YVO4 versus YAG). It seems a lot more likely to me that some of the longer IR line is being doubled instead of summed, which would add a red wavelength to the laser. Conversely, the "yellower" state could be caused by the addition of 532nm, with the "oranger" state emerging when the green fades away. Pointing it through a diffraction grating, or even at a CD would verify this. Red, or more commonly green, would start coming through in a lot of the older DPSS yellows under certain conditions.

Sta 07-07-2016 11:06 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by Cyparagon (Post 1431582)
I've never heard of a yellow randomly switching to another yellow. Coatings don't allow this, and I believe the two different IR lines required only have sufficient gain in a different medium (YVO4 versus YAG). It seems a lot more likely to me that some of the longer IR line is being doubled instead of summed, which would add a red wavelength to the laser. Pointing it through a diffraction grating, or even at a CD would verify this.

That's what I did in the video, Cyp - I pointed it through a diffraction grating. I saw no hint of red, nor green. Only a pure yellow.


Quote:

Originally Posted by diachi (Post 1431581)
May have got the temperatures the wrong way around... Got 5 thoughts going on at once here and more browser tabs open than I know what to do with. :beer:



Well that's not entirely true. My thinking is that it's producing a mix of 589 and 593 (or 1342 and 1319 I guess...) - when the temperature changes the lines gradually fade out/fade in resulting in a smooth transition between 593nm and 589nm (both there simultaneously) as one line gets stronger and the other gets weaker.

I don't think it's doing 163mW of 593 either - that's why I said I'd like to see it spectro'd and metered at the same time. :p

Certainly something interesting going on anyway.

Problem is, it isn't a smooth transition, it's an immediate jump. I'll see if I can get it to work again and this time record at 240fps.
There's definitely something diabolical at work here, and we will find it. :D


:beer:

Sta 07-07-2016 11:17 PM

Re: 589nm misbehaving - wrong wavelength!!
 
I recorded the jump at 240fps and it revealed absolutely nothing. :D
However, I was able to detect a tiny amount of 532nm when shined through a diffraction grating. It is no more than a few microwatts, however, and seems to only affect the color trivially.
No 671nm was detected. :beer:


Edit: I forgot to mention that I have a 593.5nm pen that should be arriving in a few days. Once it arrives we'll be able to solve at least one part of the mystery!

diachi 07-07-2016 11:27 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by Sta (Post 1431586)
I recorded the jump at 240fps and it revealed absolutely nothing. :D
However, I was able to detect a tiny amount of 532nm when shined through a diffraction grating. It is no more than a few microwatts, however, and seems to only affect the color trivially.
No 671nm was detected. :beer:

Ahh, yes, paid better attention this time, it isn't smooth at all. :p

I'm going to stand by my earlier reasoning - although I'm not sure how it'd be happening, as I understand things it shouldn't happen - but it is, and sometimes things that shouldn't happen do.

Had I seen 589 in person I'd have a better idea of what's going on. But it's going from more a more golden yellow to a more orange-yellow. So it's going from a shorter wavelength (somewhere around 575nm maybe?) to 589?

Fancy making a DIY spectrometer? That may help us understand what's going on. :D

Edit: Cyp does make a good point about 532nm being in there but from what you said it doesn't sound like it'd be enough to cause such a drastic change.

Sta 07-07-2016 11:33 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by diachi (Post 1431587)
Ahh, yes, paid better attention this time, it isn't smooth at all. :p

I'm going to stand by my earlier reasoning - although I'm not sure how it'd be happening, as I understand things it shouldn't happen - but it is, and sometimes things that shouldn't happen do.

Had I seen 589 in person I'd have a better idea of what's going in. But it's going from more a more golden yellow to a more orange-yellow. So it's going from a shorter wavelength (somewhere around 575nm maybe?) to 589?

Fancy making a DIY spectrometer? That may help us understand what's going on. :D

I also considered the possibility that it was going from a shorter wavelength up to 589, but the orange-yellow seems far too orange to be 589. That is what triggered my initial suspicion that this wasn't 589.
I think that with 575 to 589 the dots would have moved a lot further. And the 'golden yellow' output definitely fits the description everyone has given 589.
A DIY spectrometer would be nice, but I don't think it would be precise enough to tell us anything we don't know.

Hap 07-07-2016 11:38 PM

Re: 589nm misbehaving - wrong wavelength!!
 
When will you be receiving the 593.5 you bought Sta? Once you get it you can compare it to your Spartan :)

-Alex

Sta 07-07-2016 11:41 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by Hap (Post 1431590)
When will you be receiving the 593.5 you bought Sta? Once you get it you can compare it to your Spartan :)

-Alex

The member who sold it to me told me it'd arrive within 5-7 business days, that was one week ago. However, the tracking number still does not work. :undecided:

thebouljello 07-07-2016 11:41 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Was a defect due to a problem during the manufacturing process considered?:thinking: That would be rare but still possible.

Sta 07-07-2016 11:49 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by thebouljello (Post 1431592)
Was a defect due to a problem during the manufacturing process considered?:thinking: That would be rare but still possible.

That's certainly possible (if not probable!) and also explains the anomalous 150mW+ output. :)

diachi 07-07-2016 11:50 PM

Re: 589nm misbehaving - wrong wavelength!!
 
Quote:

Originally Posted by Sta (Post 1431588)
I also considered the possibility that it was going from a shorter wavelength up to 589, but the orange-yellow seems far too orange to be 589. That is what triggered my initial suspicion that this wasn't 589.
I think that with 575 to 589 the dots would have moved a lot further. And the 'golden yellow' output definitely fits the description everyone has given 589.
A DIY spectrometer would be nice, but I don't think it would be precise enough to tell us anything we don't know.

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.

Not sure how it'd manage to lase on both of those lines, but that'd explain it... And thinking about it that colour looks like what I'd expect ~607nm to look like.

You'd be surprised how accurate a DIY spectrometer can be. ;)

Edit: Ideas are flowing a bit better now that I can focus on one thing... :p

Cyparagon 07-07-2016 11:52 PM

Re: 589nm misbehaving - wrong wavelength!!
 
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. It wouldn't be the first time spooky shit like this happened. I've had two different occurrences of cheap DPSS green pointers being multi-line for example.

I've got a spectrometer if you ever feel like getting this metered professionally.


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