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David Notebook: Difference between revisions
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==Daily Log==
'''4/15/15'''
Been working on modulating the PCF output of the orange laser. Got the 1064 beam up and running again and locking as well as it used to. 780 was very easy to get modulated again, though it's always a little hard to actually detect with the lock-in. The 780 diode burned out--started outputting only a few mWs even at high current, but I replaced it and it's working fine again. I now have the 780, orange laser, and the HeNe aligned to the cavity using 2 flip mirrors. Each beam has two separate mirrors, but they're not all independent. Still, it was the cleanest setup I could come up with and after the initial difficult alignment it's not much of a problem. I'm trying to use a monochromator instead of the diffraction grating setup like before. I'm still chopping the beam and looking at it on the lock-in It works well enough for the 780 at least. My hope is that it will give me some sort of spectrum-resolving ability. I couldn't detect anything from the orange laser yet though--I think there's just too much unmodulated light getting through so that when I change its alignment to the cavity I'm mostly affecting how much light makes it through the monochromator. I got some low-pass filters though that should cut out everything but the modulated light though which will hopefully help. I haven't tried to make the beam-profile better match the 1064 yet either which will help increase conversion efficiency.
I've also been trying to modulate a HeNe mostly just to see if I can. It should shift to 532nm and be pretty visible, but I couldn't see anything yet. The beam profile probably isn't good though or the polarization and it's so low power, so I'm not surprised. They have some 20 mW HeNes in the optics lab maybe I should borrow. I don't want to waste too much time on this though since it doesn't really show anything different from what we've done before--it was mostly just something to do while waiting for the filters for the orange laser.
I was hoping the orange laser would be easier to detect since it's pulsed, but it seems like the pulse width is too narrow--I tried looking at it on a photodetector and it didn't seem any easier to detect than a CW beam.
'''3/16/15'''
Major findings of the last month:
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