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Thread: Frequency doubled YAG laser

  1. #1
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    Laser Warning Frequency doubled YAG laser

    Finally, I have some results on this project to share. I have been working on a frequency doubled YAG laser for some time, longer than I estimated. It is based on a modified LTI501 laser head. I had to make the lamp PSU, the acoustooptic q-switch controller from skratch and find the most suitable frequency doubling crystal in order to get something. I have posted a lot about it on LPF thread, with a lot of photos. The link to the thread is here: https://laserpointerforums.com/threa....100104/page-5

    I've reached the peak output power of about 1.5 W of green light at the maximum 40A pumping current and about 1W at 30-32A, that can be maintained more or less stable for some time. I think that this is a good result for my setup at the moment, that uses such a simple and straight-forward engineering approach. The narrow place is the laser pumping chamber itself that can't use the electric power effectively. I hope that I can modify it by installing a bigger YAG rod and getting additional power in 1064nm, that will help me increase the power of SHG.
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  2. #2
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    ... congratulations! -- top result!

    Where's the doubled beam from?

    Viktor
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  3. #3
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    The SHG converter is mounted on the OC mirror fixture from the inside, as it is intracavity SHG. SHG converter from a noname chinese YAG tattoo remover proved to be the best choice in my case.
    Attached Thumbnails Attached Thumbnails _uphlm0RYC4.jpg  


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    You always have the coolest stuff!

    Adam

  5. #5
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    Can you comment on the placement of that SHG converter relative to the beam? Was it fussy to adjust the perfect polarization angle to get the SHG crystal to behave well? I have a 1kW CW 1064nm that would be nice to find an SHG crystal for that wouldn't just explode trying to align it.

    Quote Originally Posted by Laserbuilder View Post
    The SHG converter is mounted on the OC mirror fixture from the inside, as it is intracavity SHG. SHG converter from a noname chinese YAG tattoo remover proved to be the best choice in my case.

  6. #6
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    Quote Originally Posted by liveforphysics View Post
    Can you comment on the placement of that SHG converter relative to the beam? Was it fussy to adjust the perfect polarization angle to get the SHG crystal to behave well? I have a 1kW CW 1064nm that would be nice to find an SHG crystal for that wouldn't just explode trying to align it.
    I didn't do any calculations for optimal crystal position along the laser resonator, attaching it to the OC mirror was the most comfortable option. Anyway, it is more beneficial to place it there, than closer to the pumping chamber, as the beam seems to be narrower on the OC.

    As for the polarization. Yes, I had to rotate the crystal to find the best position, but the tolerance is quite big -- about 1\10 of the full revolution angle.

    Is your laser q-switched? In a true CW lasng mode the SHG performance is very low, especially when the beam is without focusing inside the crystal.

  7. #7
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    Its "L-fold" time... probably quadruple the power by using three mirrors at the expense of divergence and Poynting Vector walk-off.

    Three mirrors instead of two.

    If you want to get really advanced:

    Attached little bit of drawing used under educational license is a quoted part of a marvelous paper on very low divergence Tem00 CW lamp pumped lasers. It simply lases so many modes in a Tem00 structure that the "Green Problem" goes away. It also corrects for the rod astigmatism from CW thermal lensing.



    Steve
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  8. #8
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    Thanks!

    L-fold or Z-fold layouts are good, but I don't have access to curved mirrors for it. It is easy to buy chinese YAG mirror sets cheaply (something like 18-20$ for a set of HR and OC), but they are flat ones. I've never seen curved among them.

  9. #9
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Look closely on Ebay, they abound from China for marker system.

    Steve
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