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How to get a blue dpss lbo crystal

toked323

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Hey i was wondering since you can buy a dpss crytal to turn infrared to green in green lasers then why cant you with blue.....it would be cheaper.....do any of you know where i can get a blue dpss lbo crytal from?

thanks toked323
 



pseudonomen137

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toked323 said:
Hey i was wondering since you can buy a dpss crytal to turn infrared to green in green lasers then why cant you with blue.....it would be cheaper.....do any of you know where i can get a blue dpss lbo crytal from?

thanks toked323
Why would it be cheaper? Yes, you can buy such crystals but I think you may be missing the point of DPSS. DPSS is not magic. You do not stick a crystal in front of IR and get blue out of it.

To create a blue DPSS laser you start with an 808nm diode, which pumps Nd:YAG. Now, this has to be in a specially aligned mirror cavity, or the crystal has to have expensive coatings on it to simulate said cavity. Normally this would generate 1064nm which doubles into 532nm green. However, Nd:YAG can be made to lase at 946nm. To do this you need the optics/coatings specially tailored to suppress gain at lines like 1064nm, while encouraging the amplification at 946nm. That 946nm line is far less efficient than 1064nm, so right there you need much more demading power/pump diode/heatsinking (the sum of which is more $$) compared to green.

Once you have all that, THEN you can worry about getting an LBO crystal to double the 946nm to 473nm and get your precious blue output.


Summary? Blue laser are expensive, and expensive with good reason! Making one yourself is not impossible, and would be an amazing learning experience, but be prepared to spend hundreds or thousands of dollars in R&D and still not have a finished/working product.
 

Hemlock_Mike

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Toked --

Pseudo just scratched the surface of what's needed to make even a greenie work. Those MCA crystals have very wavelength specific coatings to establish the cavity resonance.
Hey -- Buy one. Experiment - That's what we're about here although we do have a number of appliance opperators :mad:
You might get lucky and get something coated just right. Even if you get a green, you've done something. Carry on ---

Mike
 

BlueFusion

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I found a place to get LBO which directly doubles 808nm straight to 404. US$273 each they are NOT cheap. Thats a 4mm x 4mm x 1mm crystal.
 

philguy

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Ok, may be expensive. But then, if you could pump that with a 40W ir diode, which isn't all thal expensive, you might get a considerable blue beam, and with a bit of luck it might be considerably cheaper than a same-powered blue module.

Well, just talking here...no real idea about blue dpss, only the basic idea.
 

BlueFusion

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Thing is that crystal could THEORETICALLY handle up to about 700W of 808nm IR, WITH COOLING. With a 10% efficiency, guess where the other 36W go... HEAT! Dissipating 36W of heat from such a tiny crystal is NOT easy.
Possible but VERY VERY VERY difficult.
 

shikari_rock

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BlueFusion said:
I found a place to get LBO which directly doubles 808nm straight to 404. US$273 each they are NOT cheap. Thats a 4mm x 4mm x 1mm crystal.
Where's that? I never heard of 404nm DPSS?
 

marianne

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BlueFusion said:
I found a place to get LBO which directly doubles 808nm straight to 404. US$273 each they are NOT cheap. Thats a 4mm x 4mm x 1mm crystal.
is there really much point when you can just get a 405nm diode?
 

philguy

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yes, if you want >20mW and don't mind putting up with the excess heat or if you don't want the fiddling with beam combiners.
 

Benm

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I guess you might as well shoot for 473 nm if you are willing to go through all the trouble. ~404 nm is not a very desirable wavelenght for pointers or anything where you want the beam to be visible.

I wonder if there are any doubler crystals that can work from commonly available IR frequencies like 850 or 980 nm. Especially the last one would be interesting when doubled, resulting in 490 nm - extremely visible cyan.
 

marianne

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Benm said:
I guess you might as well shoot for 473 nm if you are willing to go through all the trouble. ~404 nm is not a very desirable wavelenght for pointers or anything where you want the beam to be visible.

I wonder if there are any doubler crystals that can work from commonly available IR frequencies like 850 or 980 nm. Especially the last one would be interesting when doubled, resulting in 490 nm - extremely visible cyan.
one step closer to my dream of a 488nm handheld!! (2nm off isn't such a big deal :D)
 

philguy

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Benm said:
I guess you might as well shoot for 473 nm if you are willing to go through all the trouble. ~404 nm is not a very desirable wavelenght for pointers or anything where you want the beam to be visible.

I wonder if there are any doubler crystals that can work from commonly available IR frequencies like 850 or 980 nm. Especially the last one would be interesting when doubled, resulting in 490 nm - extremely visible cyan.

Oh yes - from a document I just read it seems that the KTP will work at any frequency of the visible light, doubling it - but for guaranteed results you just need high enough intensities, ranging around (from what I was told) 1GW/cm² (150MW/in², for the lazy nonmetric people).
Maybe you're lucky though and it will work lower :) But that's where you need pulsed for.
 

Benm

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How does that number compare to the required power for say a 1064->532 doubling crystal found in DPSS greens?

1 GW/cm2 sounds like a crazy big figure really, even with a beam 0.1 mm in size that's still in the order of 100 kW.

I guess there must be a big catch somewhere, as you rarely see any visible DPSS lasers on the market than 532 or 473 nm.
 
S

SenKat

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Wilfred - valid points, all - BUT that "module" as described is simply out of a low powered pointer that someone scrapped to make cash - I would not count on it actually functioning well :( Even IF the crystals were of a higher quality - it would still be a TOTAL pain to align properly, and to have functioning anywhere near it's capacity. I have done LOTS of experimenting with the various crystal sets I have ran across, and let me tell you - without the patience of Jobe, you are not going to get ANY green light, period ! :p Itsa royal pain, TBH...but it is kinda fun to try - I do fully encourage anyone with a low temper threshold to attempt this :)
 




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