Coherent Genesis 577nm Laser (FINALLY)

[paul1598419]

Yes, I knew you said it had an O2 absorption device, but you also said it has a desiccant too. Those are normally used when there is something that will absorb water. But, an LBO crystal won't. I have seen them used for 532nm, but since this is a 577nm one and likely has a crystal that absorbs water, that was the source of my skepticism.

 

[ultimatekaiser]

<post removed>

I'll look into it. I remember something about LBO being water sensitive, but not as much as BBO, I'll see what I can find. I'm finding lots of conflicting info. Also, I stand corrected on this one. My melles 561 does say it uses an LBO but does have dessicant. However digging into this other 577 there is only an oxygen absorber, as well as in the green. there are two in each. I thought one was silica gel, it is not.

Edit:

Found this:
Laser Focus World - March, 2003

BBO, LBO
The introduction of beta barium borate (BBO)
and lithium triborate (LBO) in the late 1980s
provided a combination of nonlinear
efficiency and high damage
threshold that significantly
accelerated NLO development. Both materials are
transparent well into the ultraviolet. Lithium
triborate has the highest damage threshold of
all commonly used NLO crystals, making it the
material of choice for high-a
verage-power applications.
Both materials are used to produce wavelengths
shorter than 300 nm, but LBO has a lower
birefringence that limits its UV phase-matching
to certain combinations of longer wavelengths. It
is often "temperature tuned" for phase-matching;
that is, heating the crystal to a temperature at
which its refractive index is the same for the
fundamental and harmonic light. Compared to BBO,
it has a significantly wider acceptance angle.
The birefringence of BBO gives it excellent phase-match
capabilities, enabling it to produce
tunable radiation from the near infrared into the
UV. It is commonly used in parametric conversion,
and for the generation of higher harmonics of neodymium
lasers. Both crystals are slightly hygroscopic, and are relatively soft.

Adding cesium to LBO produces CLBO, a soft a
nd hygroscopic material that nevertheless has
grown in popularity for producing shorter wavele
ngths. The combination of CLBO properties
allows a severalfold improvement in NLO efficiency.

 

[trinh hong phuoc]

a great color ,thank you for sharing

 

[paul1598419]

I was going to suggest a BBO crystal, but since you haven't found any conclusive evidence that LBO is hygroscopic, which matches everything I have found on it, and the fact that there is no desiccant in the lid, it seems like a nonissue now.

 

[ultimatekaiser]

I was going to suggest a BBO crystal, but since you haven't found any conclusive evidence that LBO is hygroscopic, which matches everything I have found on it, and the fact that there is no desiccant in the lid, it seems like a nonissue now.

Yeah, we're honestly off topic. I'm finding lots of papers that say it is, and some manufacturers say yes, and a couple others list it as no. Scientifically speaking it should be. Whether it's enough for concern seems to be the issue of debate. I dunno what you've read but most of the makers I've all asked/worked with say they are weakly hygroscopic and recommend to provide it with a dry environment, including castech, northrop, and crysta-laser, which are huge crystal makers, so forgive me if I believe them over a forum member. But I think we can agree that regardless, if it's in a sealed environment, it really shouldn't matter and leave it at that.

 

[diachi]

I was going to suggest a BBO crystal, but since you haven't found any conclusive evidence that LBO is hygroscopic, which matches everything I have found on it, and the fact that there is no desiccant in the lid, it seems like a nonissue now.

Everything I've ever read or been told says LBO is hygroscopic. Less so than BBO, but hygroscopic nonetheless. Have been warned to add fresh desiccant packs to THG YAG heads that have been opened and to never buy one used that has been opened, specifically for that reason. I would trust that those sources due to their extensive experience.

Coherent may have opted not to use a desiccant for whatever reason, perhaps it's more of an issue when you're doing frequency tripling down to the UV compared to visible stuff like 577.

 

[Encap]

Everything I've ever read or been told says LBO is hygroscopic. Less so than BBO, but hygroscopic nonetheless. Have been warned to add fresh desiccant packs to THG YAG heads that have been opened and to never buy one used that has been opened, specifically for that reason. I would trust that those sources due to their extensive experience.

Coherent may have opted not to use a desiccant for whatever reason, perhaps it's more of an issue when you're doing frequency tripling down to the UV compared to visible stuff like 577.

Agree, most sources talk about LBO as hygroscopic some say moderately some weaker.
Some vendors sell ovens to remove foggy conditions of polished faces due to being exposed for some time to ambient conditions

"LBO is a moderately hygroscopic crystal. The AR coating is not a 100% longterm protector of polished LBO surface from atmospheric moisture. Therefore, a rule of handling LBO crystal is to minimize its contact with humid environment. Mar 4, 2016"
~ From google search of "LBO laser crystal hygroscopic"

 

[diachi]

Agree, most sources talk about LBO as hygroscopic some say moderately some weaker.
Some vendors sell ovens to remove foggy conditions of polished faces due to being exposed for some time to ambient conditions

"LBO is a moderately hygroscopic crystal. The AR coating is not a 100% longterm protector of polished LBO surface from atmospheric moisture. Therefore, a rule of handling LBO crystal is to minimize its contact with humid environment. Mar 4, 2016"
~ From google search of "LBO laser crystal hygroscopic"

RP Photonics says much the same thing, and have been told the same by Steve Roberts and others who work hands on with this stuff on a frequent basis.

 

[paul1598419]

On United Crystals site for Lithium triborate crystals at the bottom of the listed properties for LBO crystals.........Hygrscopic Susceptibility: NO.

https://unitedcrystals.com/LBOProp.html.

 

[ultimatekaiser]

Everything I've ever read or been told says LBO is hygroscopic. Less so than BBO, but hygroscopic nonetheless. Have been warned to add fresh desiccant packs to THG YAG heads that have been opened and to never buy one used that has been opened, specifically for that reason. I would trust that those sources due to their extensive experience.

Coherent may have opted not to use a desiccant for whatever reason, perhaps it's more of an issue when you're doing frequency tripling down to the UV compared to visible stuff like 577.

It is.

On United Crystals site for Lithium triborate crystals at the bottom of the listed properties for LBO crystals.........Hygrscopic Susceptibility: NO.

https://unitedcrystals.com/LBOProp.html.

Yeah I saw that too. I don’t know why they say that... although in their defense LBO as far less susceptible to moisture than BBO

 

[icecruncher]

For some reason, it reminds me of the halfnotes I've seen.

yellows and orange spectrum is my favorite, thanks for sharing and the excellent, explanation of the OPSL system. I appreciated learning about these.

Hard to imagine a 3w true yellow. That has to be absolutely gorgeous in person. Even the milliwatt ones I've seen in person are stunning. Liquid sunshine

 

[ultimatekaiser]

Yeah it’s pretty interesting because I have a one watt green genesis head and that is much more intense to see due to it being single mode and a brighter wavelength. It would probably be incredibly spectacular at night. The yellow three watt has a wider beam. so while the spot is intense, the beam covers a wider area, and isnt as bright as it could be. So it goes to show as a perfect example that power isn’t everything.