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Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
A friend and I are building a Nd:YAG laser for metal cutting - he's doing the mechanicals, I'm doing the electronics. We have the YAG rod (110mm x 5mm, 1% doping) but not the resonator mirrors. Intention is to pump this sucker with 600W of 808nm diode laser bars.
The question I have is : does anyone here know how to work out what the output coupler transmission should be? Or know where to find that calculation - i.e. any good books? The searches I've done so far have not been very fruitful, the only information gained is that choice of output coupler is important to get maximum power, and is dependent on the YAG rod and pump method.
Registered Member #3215
Joined: Sun Sept 19 2010, 08:42PM
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Posts: 780
sam's laser FAQ :) this is very specific and reading it will enable you to choose your keywords while searching for some research papers
it depends on the rod geometry, doping, q-switched or not, actively or not, pump geometry, thermal lensing, mechanical constraints, and modes wanted (assume gaussian is a minimum for focusing on spots smaller than 500µ)
if you hadn't already chosen the rod, I'd have advised going Cr4+:YAG:YAG:Nd:YAG for passive q-switching and diffusion bonding for greater efficiency
otherwise if you want some pulsed operation which is really what you need for cutting, you have to use an intra cavity q-switch like one from a laserscope YAG or other medical head
this level of power yields easily 250W of 1064nm light, and the equivalent in scattered 808nm and fluorescence, so I hope you are aware of the dangers... OD9 in the range 808 and 1064 is a mandatory protection, with closed goggles, and protected room
if anyone goes in the room when you're not expecting it, there is a 75% chance of definitive eye injury just by entering the room and being hit by scatter (it means wherever you're in the room there's more than one chance per two to be hit by at least 5W of IR radiation, which is less than 1% what you'll have your face over)
good luck on this project though, that's not something everyone will do and you'll need time and help even if you know your business
laserman532 and mixedgas from photonlexicon might be of a great help
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
Thanks for the comments, that gives me a starting point. We hadn't planned on q-switching to start with, but it is something I think we'll need. We are well aware of the safety issues surrounding lasers, but its good to have it noted in the thread anyway. My co-conspirator has found a very technical e-book (some 400 pages or so) so I guess I have some bed-time reading to do.
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Nd:YAG laser : choosing resonator output coupler?
