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David Notebook: Difference between revisions
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==Daily Log==
'''5/19/14''' After initial alignment of 1064, the 633 beam could easily be seen when ramping the cavity without any adjustment. It seems very repeatable, but also suggests that the power isn't close to optimized yet since there was no noticeable difference in brightness after a weekend to drift. We spent most of the day trying to increase the 633 beam so that we can see it on an OSA. First we worked on the 780 alignment, and adjusted it while looking at the 633. A full "beam-walk" was too difficult without some sort of numeric measure of power, but by only adjusting the vertical and horizontal of one mirror we made the 633 substantially brighter. At one point, the 633 signal disappeared and moving to different cavity modes didn't help. I'm not sure why this happened, but this was solved by slightly translating and rotating the prism and then adjusting the beam blocks for the 807/780/1064 beams. This was an easy process to get the 633 beam back, which is encouraging.
We also doubled the power of the 780 immediately after the TA (see [[David_Notebook#780_Laser_Notes|780 laser notes]]). We still couldn't see a signal on the OSA though, even with lots of averaging and with the beam locked. But looking at the coupling fiber when ramping the cavity, we could clearly see the 633 beam flashing above a constant background of 780. Putting in an 780 notch filter and a 633ish bandpass filter (borrowed from 1st floor John), we know have what seems to be a flashing 633 signal with very good contrast (i.e. against very little background). We hope that this will be easier to optimize and finally detect with the OSA. It's confusing that the 633 signal is so visible even through the fiber and when not looking directly at it--how sensitive is the eye to 633, or could we be having equipment issues?
'''5/16/14''' 1064 laser was notably better today--easier to align, better peaks, and less prone to drift. We slightly translated and rotated the prism until the 807 beam coming out seemed more defined. It looked much better than the previous day, but this might be due to the improvement in the 1064 beam. We built a fort (what's took [[Jared]] so long with his?) to block most external light in the lab and blocked the 1064 and 807 beams from the prism, as well as the small amount of 780 that was getting through the notch filters. Any 633 should have greater angular separation from the other beams than the 780, so we were careful to only put the beam blocks right to the edge of the 780 so as to avoid blocking any 633 that might be generated. We then used the camera to overlap the 780 and 807/1064 beams on the 1064 side of the cavity. This worked well today and was an easy process once we made sure no beams were clipping.
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