193nm Q-switched Yag system

[a***@galacticscientific.com]

Hello friendly sci.optics community.

I am fortunate enough (though in many ways, not so much) to be attempting to restore a very interesting Q-switched Yag system.
I'm wondering if anyone out there has some experience with such beasts.

I had it working fine but a relocation has changed that.
Temperature in the new location is around 5 degrees C cooler, so everything needed readjusting, but IR came good eventually from the flashlamp pumped source.
I can say the IR generation side is now OK'ish. Should generate 300mJ, I get 250.
The 532nm SHG output is low however at 20mJ.
No matter what angle I move the thing or set the adjustment, that's as good as it gets. It looks OK, clear path, no frosting.
So I was wondering if anyone has a good guide to testing and/or repairing harmonic generators generally as aside from adjusting them, I've never tried to seriously test and/or repair one. If indeed it has a problem, maybe I'm not testing it properly...

[Phil Hobbs]

Post by a***@galacticscientific.com
Hello friendly sci.optics community.
I am fortunate enough (though in many ways, not so much) to be attempting to restore a very interesting Q-switched Yag system.
I'm wondering if anyone out there has some experience with such beasts.
I had it working fine but a relocation has changed that.
Temperature in the new location is around 5 degrees C cooler, so everything needed readjusting, but IR came good eventually from the flashlamp pumped source.
I can say the IR generation side is now OK'ish. Should generate 300mJ, I get 250.
The 532nm SHG output is low however at 20mJ.
No matter what angle I move the thing or set the adjustment, that's as good as it gets. It looks OK, clear path, no frosting.
So I was wondering if anyone has a good guide to testing and/or repairing harmonic generators generally as aside from adjusting them, I've never tried to seriously test and/or repair one. If indeed it has a problem, maybe I'm not testing it properly...

I've been mostly a CW guy overall, but a decade or so back I acquired a
modelocked, 20-Hz, lamp-pumped, tripled-YAG-pumped, seeded optical
parametic generator (OPG) with difference-frequency generator (DFG) that
would produce ~20 ps pulses anywhere from 380 nm to 10 um, excluding a
couple of small places where degeneracy occurred (near 710 nm mostly).
It was from Ekspla (based in Lithuania), and cost about a third of the
nearest onshore equivalent.

It was a thing of great beauty when it worked, which was, well, usually.
In my naivete` I thought it would be the nonlinear stuff that would be
the issue, but it turned out to be mostly the pump laser.

So kibitzing about your Q-switched system, I'd be looking for anomalies
in the pump, e.g. long tailed pulses fooling you into thinking that your
peak power is in spec when it isn't.

Cheers

Phil Hobbs