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David Notebook: Difference between revisions
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==Daily Log==
'''10/22/14'''
I'm not sure what was going on with the laser driver, maybe a loose cable? I haven't had that problem again in the last week. I got the 1555 lock working better and got to about 600-700 mW of power. However, when it was locking well and the noise was low, the transmitted signal looked like a sine wave with a frequency of 1 kHz. Clearly the noise I was having was causing a problem. It turned out that the RF generator was putting side bands on the signal at 1 kHz. I swapped RF generators which seemed like it should help a lot. I got up to ~850 mW, but I think there is more optimization to be done since the phase delay was changed. The lock is pretty inconsistent from day to day, but I decided to put it aside and get the 1064 working again and then add gas before trying to optimize the locks much more.
The 1064 was much easier to get locking, although the transmitted power is low. Only around 70 mW after playing with most of the parameters fairly extensively. I'm not sure why it is lower, but the lock is pretty stable.
I'm still confused as to why I don't see the changes in error signal that I would expect when I change the phase delay. There doesn't seem to be much difference on both the 1064 and 1555. This is definitely something to focus on because it seems like it could be having a big effect on the lock.
'''10/15/14'''
I tried to follow the various signals through all parts of the PDH circuit. I made slight adjustments here and there, and most notably added some BNC length to change the phase delay on the local oscillator. I also turned off the integrator on the lock-box and so was just using the proportional gain. The error signal should be linear near resonance, so do we even need differential and integral adjustments? I saw the best performance yet, with powers over 300 mW and fairly consistent.
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