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Ashton
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likewhat
55mW Advanced Wicked Laser
Joined: 10 Jun 2007
Posts: 62
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 Posted: 8/30/07, 8:49 PM Post subject: |
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| That would be a pretty sweet if you doubled it to get a blue laser, there should be more than enough power. |
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Ashton
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| Posted: 8/31/07, 2:01 AM Post subject: |
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It's not an issue of power as much as finding a crystal that resonates with 927nm, the way I understand it, there's a range that each crystal resonates with (I think it's 20nm, but it might be as high as 50 or 100nm) so the crystals for 808nm that make green will not resonate with 927nm. It takes a different crystal to do that, sadly...
though I could be completely wrong, and if I am my third buy after this laser and a PSU will be an el-cheepo green ebayser to harvest the KTP crystals! lol (though I'm sure I'm wrong - it cant possibly be this easy) |
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likewhat
55mW Advanced Wicked Laser
Joined: 10 Jun 2007
Posts: 62
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| Posted: 8/31/07, 9:00 AM Post subject: |
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If you doubled 808 you would get 404 which is blue, not green. Green is made by doubling the 1064 nm light that the ND based gain medium lases at. The power is important because the efficiency of the second harmonic generation is dependent of the intensity of the light, even if you have a crystal that is poorly matched to what you are doing, a high intensity beam will yield more doubled light then a low intensity beam. High intensity is easier to get with more power.
I dont think KTP is used for making blue light, it is something else that they use for making blue light from Ti Sapphire lasers. You can get a crystal to double just about anything, you require that a phase matching condition is met for the process to occur, this can be done by placing the crystal structure at certain angles with respect to the incoming beam. |
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King K
Wicked Lasers God
Joined: 06 Sep 2006
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| Posted: 8/31/07, 2:24 PM Post subject: |
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| likewhat wrote: |
| If you doubled 808 you would get 404 which is blue, not green. |
It's actually violet, near-UV. Definitely not blue.
| likewhat wrote: |
| I dont think KTP is used for making blue light, it is something else that they use for making blue light from Ti Sapphire lasers. |
Most blue DPSS lasers use Yttrium Garnet (Nd:YAG) and Lithium Triborate (LBO) crystals, I think that the Nd:YAG crystal lowers the wavelength from 808nm to 978nm or something like that, then the LBO doubles it to 473nm, I'm not really sure about this though.
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likewhat
55mW Advanced Wicked Laser
Joined: 10 Jun 2007
Posts: 62
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| Posted: 8/31/07, 7:26 PM Post subject: |
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| King K wrote: |
Most blue DPSS lasers use Yttrium Garnet (Nd:YAG) and Lithium Triborate (LBO) crystals, I think that the Nd:YAG crystal lowers the wavelength from 808nm to 978nm or something like that, then the LBO doubles it to 473nm, I'm not really sure about this though. |
The Nd yag is what is actually lasing, the 808 nm diode is to get a population inversion in the lasing medium. The yag can then lase at certain lines, 1064 nm is the most popular, but it can also lase at the 978 nm or whatever line. The crystal then is used to double the 1064 or 978 or whatever else to half its wavelength.
I have never seen a blueray diode which I guess is at 405 nm so I dont really know what it looks like, but apparently violet as you said. I was just mentioning that the above poster said the 808 is doubled to green, if you doubled 808 it would be 404 which is not green was where I was going with that.
There seems to be some confusion in general about how these lasers work. The diode in them just takes over the job of what used to be a flash lamp or arc lamp that pumped the gain medium (typically some Nd based thing), the gain medium then lases at some transition in the IR which is then doubled to get a nice green or blue color. |
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