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Entry  Thu Mar 24 02:10:14 2011, tara, Notes, RefCav, Cavities' pole rcavtf.pngacavtf.png
    Reply  Thu Mar 24 22:54:10 2011, tara, Notes, RefCav, Cavities' pole 1_RCAVTF.png4_RCAVTF.png2_RCAVTF_120PD.png
Message ID: 553     Entry time: Thu Mar 24 22:54:10 2011     In reply to: 552
Author: tara 
Type: Notes 
Category: RefCav 
Subject: Cavities' pole 

I replaced thorlabs PD55A for ACAV_RCTRANSPD with PD36A, ACAV TF now looks reasonable.

From a quick look, ACAV pole is 57.4 kHz (previous result, 54kHz), RCAV pole is 39.7 kHz (previous result, 38kHz).


1)result for RCAV TF, with RCAV's PD55A for RCAV_RCTRANSPD




2) For ACAV, I used PD36A to measured ACAV_RCTRANSPD, and its TF. 

 However, when the spotsize is too small, the result looks weird (like yesterday,) so I moved the new

PD where the spot is not too small and measured the TF again to get the reasonable result.

For the original PD55A for ACAV_RCTRANSPD, I also tried moving it for various spotsizes,

the results are still bad (look like that from yesterday), so I decided to go with the new PD.




3) As Frank suggested that I can use the 120 MHz PD for beat, to measure the TF, I also tried that.

   The beam from ACAV was blocked while I measure RCAV TF, and vice versa, the results are quite similar for

both RCAV and ACAV, here I show only the result from RCAV.

I'm not sure if this means the spotsize on 120MHz PD for beat is too small or not. This might worth checking out.







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