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Entry  Wed Sep 7 22:41:44 2011, frank,tara, DailyProgress, , Two cavities are in the same chamber P1040900.JPG
    Reply  Thu Sep 8 20:53:17 2011, tara, DailyProgress, RefCav, frequency difference 
       Reply  Fri Sep 9 01:45:40 2011, Frank, DailyProgress, RefCav, frequency difference 
       Reply  Fri Sep 9 01:53:21 2011, Frank, DailyProgress, RefCav, frequency difference 
       Reply  Fri Sep 9 22:53:32 2011, frank, tara, DailyProgress, RefCav, frequency difference 
    Reply  Mon Oct 3 23:54:19 2011, frank, tara, DailyProgress, , re mode matching 
       Reply  Tue Oct 4 23:20:57 2011, frank, tara, DailyProgress, , re mode matching 
Message ID: 672     Entry time: Fri Sep 9 01:53:21 2011     In reply to: 669
Author: Frank 
Type: DailyProgress 
Category: RefCav 
Subject: frequency difference 

dL~200nm + n*532nm, so you can't say what the common mode suppression really is. The only thing we know is that the length are not off by 1mm or so (which you would see and easily be able to measure), but it could be anything below that. Next time we open it we should use a good digital caliper and measure the actual lengths. But we don't have one which is long enough.

Quote:

 use df/f = dL/L, the differential length between the two cavities is   dL =  df * L * lambda / c ~ 0.2 micron.

So common mode suppression for thermo-elastic or cavity sagging due to seismic can be approximated to be ~ dL/L = 0.2 micron / 0.2 m =  1e-6.

 

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