David Notebook

Daily Log

5/15/14 1064 laser still seems somewhat different than usual, but aligned more easily than yesterday. It was still more prone to drift than was typical. Attempted to overlap 780 and 1064/807 beams on the 1064 side of the table using the camera in two locations. However, the beams were clearly not overlapping on the 1555 side after this, so we did a visual alignment on both sides of the cavity. The 1064 is too dim to see on the 1064 side past the dichroic, so we aligned to the 807 since they should be in the same place. We added in two 785 notch filters before the prism to make it easier to look for 633 generation. The 780 beam was slightly clipping the prism (and so any 633 might be also), so we adjusted the prism. The very defined 807 sidebands we saw yesterday were worse afterwards and the number of sidebands we saw didn't match the number seen with the OSA when immediately switching between the two. No beams are clipping on any optics as far as we can tell, so the angle must not be quite right with the prism and we will try to find a better position tomorrow.

Got ice cream for employee appreciation day. Josh, Nick, and I were more than willing to wait in the 10 minute line for unlimited free ice cream, but Jared and Zach quickly left. "Captain No-Fun" now redirects to Jared's page. Nick believed sherbet and ice cream to be synonymous, which was proven incorrect.

5/14/14 1064 laser was more difficult than usual to align, was very prone to drift, and only locked passably well. Gas pressure is about 0.3 atm. Josh says it's been like this for a few days, although it seemed to show slight improvement in the afternoon. We set up a mirror on the 1064 side so that we can send 807 from the cavity to a fiber launch or a prism. Despite having the dichroic as one of the coupling mirror to the cavity, on the Saffman group's OSA, we could see all 3 beams with rotational sidebands (should only by 807, but 1064 and 1555 were about the same power as 807 instead of much stronger). It seemed there were some only vibrational modes too, but we haven't tried to repeat this yet.

Putting in a filter dropped the 807 signal by about 10 dBm and made the 1064 and 1555 no longer visible on the OSA, however 1064 could still be seen very faintly with the IR viewer after the prism. We're confident we're seeing pure 807 after the prism due the to OSA signals and since we can clearly see 1064 and 807 diverge. Sending the 807 about 8 feet away to the wall, the separation between 807 and 1064 is about a foot. Depending on the mode, we see 1-2 or 5+ sidebands on 807 over about an inch.

Froze snack banana for 10-15 seconds in nitrogen. Ice clearly formed on the peel, but the interior was only somewhat cold. Will try for 30 seconds next time.

780 Laser Notes

There should be about 2 mW of power going into the TA. 5/15/14, increased 780 Laser current from 43 mA to 65 mA and adjusted the waveplate to continue sending 2 mW to the TA and the rest of the power to a fiber. Locked the waveplate at the right position--do not adjust without decreasing laser current.

≈1800 mA max to TA