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FrozenGate by Avery

Hmm. LG Rigel just... stopped working.






I do believe you, I'm just shocked that all the threads involving green lasers never mentioned this, I guess they're out of date xD

Btw, this might sound stupid, but what does this nomenclature means? I mean, what does x:y mean?
 
x:y.. x is the dopant, (the neodymium in Nd:YAG or Nd:YVO4) and y is the host crystal (The YAG or YVO4). The dopant is what actually lases, the host crystal provides a molecular lattice for the dopant atoms to cling to. The dopant and host crystal atoms can interact during the lasing process, which results in slightly different lasing lines depending on what dopant and host crystal are being used. The : merely helps signify this arrangement.

Nd:YVO4 = Neodymium doped Yttrium Orthovanadate

Nd:YAG = Neodymium dopde Yttrium Aluminum Garnet

Gd:YVO4 = Gadolinium doped Yttrium Orthovanadate

Ti:Sapph = Titanium doped Artificial Sapphire

etc..
 
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ElektroFreak said:
All I can do is speculate. 589nm is the same wavelength as the "sodium line" guide stars observatories use to excite rare gasses in the upper atmosphere. These lasers use bismuth doped fiber or raman shifting in fiber to generate 1178nm light which is then frequency doubled using standard non-linear crystals (LBO, KTP) to produce 589nm light. This process is a bit more complex than we'll be seeing in a pointer or portable, and really more complex than pretty much any Chinese company is going to tackle.

There have been some new lines (I use the word new very loosely since I really don't know just how new they are... new to most of us would be more accurate) being discovered in Nd:YVO4 that *might* include a line at 1178nm, which would make the whole thing very practical (457nm blue lasers are becoming very popular and powerful and are a result of doubling the 914nm line in Nd:YVO4.. as opposed to doubling the 946nm line in Nd:YAG to get 473nm. 457nm lasers can potentially produce tens of watts of power, impossible with 473nm.). Nd:YVO4 is a better candidate than Nd:YAG for use in simple DPSS lasers because it has a wider pump absorption range (meaning the 808nm pump diode need not be so precisely temp. controlled) which makes it much more stable. Also, some of it's lines are quite powerful, resulting in some very cool new color possibilities for high-powered lasers. As previously mentioned, it also provides other lines of output than just 1064nm which makes a few new colors possible through doubling. No data that I could find shows a 1178nm line, but this stuff is all pretty new still. Data in the public domain isn't likely to have such info, but the fact that the Chinese are pushing 589nm tells me that there must be a relatively simple way to do it.

It could also be sum-frequency generation just like 593.5 (a VERY good possibility, perhaps the most likely) only using Nd:YVO4 instead of Nd:YAG, thereby providing slightly different wavelengths resulting in a slightly different shade of yellow.

I'm nearly 100% sure the key lies in the use of Nd:YVO4 or Gd:YVO4 instead of Nd:YAG. Most green DPSS have been using Nd:YVO4 for some time now, and that's a big reason why they're inherently much more stable than most other DPSS lasers, so applying the same tactics to the design of other colors will lead to better stability from simpler cavities.. in other words, it's just perfect for Chinese lasers.
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This might have to do with why the 594's have such higher power outputs recently. I called LG for some info about the new Rigels recently and they told me that the 594's are getting much, much higher powers and are much more stable now due to CNI's using new crystals.
 
quadcam said:
This might have to do with why the 594's have such higher power outputs recently. I called LG for some info about the new Rigels recently and they told me that the 594's are getting much, much higher powers and are much more stable now due to CNI's using new crystals.
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I am unaware of any large power increases in 593.5nm (although that doesn't mean they haven't been happening, I don't have access to quite a few data sources on these subjects) so I suspect some terminology might be getting mixed up somewhere on LGs side of things. The only way a power increase will happen with 593.5 is with improved crystal purity and better control over the crystals, the former being quite likely but providing only small gains, and the latter being unable to fit in a pointer.

It's far more likely that they are referring to 589nm rather than 593.5, as the color is all but indistiguishable to the naked eye.
 
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ElektroFreak said:
I am unaware of any large power increases in 593.5nm (although that doesn't mean they haven't been happening, I don't have access to quite a few data sources on these subjects) so I suspect some terminology might be getting mixed up somewhere on LGs side of things. The only way a power increase will happen with 593.5 is with improved crystal purity and better control over the crystals, the former being quite likely but providing only small gains, and the latter being unable to fit in a pointer.

It's far more likely that they are referring to 589nm rather than 593.5, as the color is all but indistiguishable to the naked eye.
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That could very well explain it too. I think that if someone orders a new Rigel and it has the CR2 host like an Aquarius, then we'll know what's up. If they truly do have 594's that can average 20+ mW though, I wonder how exactly they pulled it off.

Possibly a spectrometer is in order....
 
20mW at 593.5nm would be only a small improvement over what we have now, so perhaps they are just using improved crystals. A big improvement would be something like150mW or more..
 
ElektroFreak said:
20mW at 593.5nm would be only a small improvement over what we have now, so perhaps they are just using improved crystals. A big improvement would be something like150mW or more..
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I know a lot of guys are peaking at 15 or 18 mW with the 594s, but LG is claiming averages of 20+, with peaks in the 40mW range. We'll see I guess. I'm hoping for the best, expecting more of the same.
 
General thoughts on 593.5nm and 589nm:

593.5nm systems are capable of several watts now with relatively small crystal sets. The 589nm process is a sum frequency generation process like the 593.5nm. If I remember correctly, there was a patent contention regarding 593.5nm systems. They seem to be everywhere now so that must have been cleaned up.

General thoughts on lasers and temperature:

I've done some stuff with military laser systems. All larger DPSS and diode lasers systems that operate in the field (other than aiming lasers on rifles, IR or othewise, and designators) have heating and cooling systems installed because DPSS and Diode laser operation is so sensitive to temperature gradients. They also have systems to control condensation and humidity. Poor little pointers really don't stand much of a chance in the wild unless handled with kid gloves.

Regarding 593.5nm systems and temperature:

The 593.5nm process is very tight in tolerance as it essentially runs two laser processes in a single resonator, plus the summing and single harmonic generation of the non linear optic. This gives the system ample opportunity for the beam to walk off as the crystalline structure changes slightly with temperature. The optics also change shape and the cavity waist shifts wildly with the slightest change. This can cause only the primary line to lase resulting in just 532nm emission or no emission at all.

Nd:YVO4 vs Nd:YAG

Nd:YVO4 is the preferred medium in smaller lasers due to lower lasing threshold and better thermal characteristics. Plus the output is polarized versus YAG. There are similar media with other dopants providing other wavelengths but Nd:YVO4 is preferred for 1064nm and other Nd based lasing lines.
 
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MrGreenJeans said:
General thoughts on 593.5nm and 589nm:

593.5nm systems are capable of several watts now with relatively small crystal sets. The 589nm process is a sum frequency generation process like the 593.5nm. If I remember correctly, there was a patent contention regarding 593.5nm systems. They seem to be everywhere now so that must have been cleaned up.
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Where (outside of a university laboratory) would one find a commercially available 593.5nm laser that produces multiple watts? Links please!
 
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Yes, you are correct. I cannot link any commercially available 3 or so watt system that I am aware of. All I can say is that I have seen them in a lab setting. The commercially available 593.5nm are on the order of a watt. The 593.5nm are becoming very popular in biomedical research laboratories, specifically neuroscience labs. The real drawback for anyone wishing to purchase 593.5nm is the heavy cash outlay.
 
At this point we can offer 593.5 nm modules up to 800 mW, but you don't want to know the price. Let's just say that the only people buying them are government labs and well-funded universities.
 
Missed this thread the first tome around, but I can agree my CNI 593.5 and 473 are both temperature and battery fickle. They can handle one being non-perfect, but not both.

My 473 is actually a little more temperature sensitive as far as power, but it lases more reliably. On a cold day, it'll be about 1/4 brightness until I warm it up in my hands some, but it'll usually lase reliably, even if less powerful. The 593.5 is more fickle about whether it lases or not with a cold day or low batteries.
 
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