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--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 18:00, 19 May 2014 (CDT)
We observed some decent locking of the SHG cavity today. At highest, we saw intermittent power of about 9mW w/ about 65mW of 1055 incident, which is a pretty decent conversion ratio of ~14 or so. Observations/issues
* Piezo is oscillating which is lowering output power. When the error signal gain is turned down, we see higher intermittent power but the lock is not very stable and drops. With higher gain, the oscillation is very pronounced.
* Also put in place the fast feedback circuit to the laser driver, does not seem to help, in fact turning up the gain kills the lock. There could be many reasons for this. I am wondering if the phase is not correct. I would think it would be the same as the slow feedback branch and two inverting amplifiers shouldn't mess it up, but i would like to check this. Perhaps there is an issue with using long BNC and/or i would think that the bread-boarded circuit would be more susceptible to crappy performance at fast feedback frequencies. I do want to get this straightened out soon so i can order the board and get the permanent circuit built.
* Also, it's becoming increasingly clear we should use a different piezo, something with higher resonant frequency would be very nice/easier to work with. I don't think we need the travel that the current piezo stack provides anyway.
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