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Message ID: 1865     Entry time: Thu Aug 17 12:52:51 2017
Author: Craig, awade 
Type: DailyProgress 
Category: RefCav 
Subject: Cavity Scan 

I wrote a script which scans the laser slow control voltage and records the transmission power.  Last night, we scaned the lasers over the entire -10 to 10 volt laser slow control for both cavities looking for 00 mode resonances.  I scanned from -10 to 10 volts using increments of 0.0001 at a step rate of 10 Hz. 

The laser is not given much time to thermalize, so the resonance voltage values reported in the plots below are not 100% accurate, but they give a good ballpark (in a test I ran, the reported value of the resonance is around 0.003 volts greater than it's true value at this increment value and step rate.)

Recall that the FSR of our L=3.67cm cavities is around 4 GHz.  Each of the tallest peaks representing a 00 mode resonating in the cavity should be separated by this frequency as the laser frequency changes.

Next step is to find two of these modes which produce a beatnote in a "stable" laser region as examined in elog 1863, locked the cavities, and look for a transmission beatnote.

Also attached is a tar containing (1) the data, (2) the plots, and (3) the python scripts used to take the data on acromag2 (CavityResonancesFinder.py) and plot the data (txtPlotter.py).

Linear Y-axis on a cavity scan!!! Ahhhhhh, no!!!!   https://www.mathsisfun.com/algebra/logarithms.html

Attachment 1: Aug-17-2017_115409_SouthLaserSlowControlVoltageVsTransPower.pdf  122 kB  | Hide | Hide all
Attachment 2: Aug-17-2017_120200_NorthLaserSlowControlVoltageVsTransPower.pdf  254 kB  | Hide | Hide all
Attachment 3: CavityResonances.tar.gz  1.471 MB
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