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David Notebook: Difference between revisions
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==Daily Log==
'''11/17/14'''
I've been mostly still trying different locking settings. The 1555 is amazingly inconsistent and I'm not sure what's really changing day to day. Both locks work better under lower pressure though, so I've been trying to find a good compromise between getting 633 generation and easy locking. 0.38 V (0.05 atm) seems like a good spot. There's 633 at a fair number of cavity modes, and it's easily visible in mirror or on the photodiode. I'm going to stick just at this pressure for a while and maybe I'll be able to learn more about locking just at this pressure.
It also occurred to me that we might be able to run the lasers are higher power. The limiting factor is the isolators, but the 1064 one is rated for 60 W and 500 W/cm^2. We're obviously under 60 W, and I think our intensity is ok too At 30 W of input, we would need a beam larger than 1.4 mm. I'll measure it when I get a chance. The isolator's aperature is 4.7 mm, so we could always expand the beam and re-collimate it after. That would be a lot of trouble, but we could increase our single beam conversion efficiency by 50%.
'''11/5/14'''
I'm not sure what happened, but something must have gotten bumped and the 1555 was completely misaligned--no cavity peaks or anything. It was good practice at setting that back up at least. The best way seemed to be to turn the power way down and look at the incident beam and reflected beam with the card and try to overlap them in two places. Then I moved the transmitted photodiode and took off all the filters/covers and put it right at the transmitted side of the cavity. Using the HeNe was helpful for making sure the photodiode was pretty much aligned to where the 1555 beam would come out. Turning the power all the way back up and making small adjustments with the walking mirrors usually got some very small peaks which could them be optimized.
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