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Entry  Wed Nov 3 01:22:57 2010, tara, Notes, PMC, TF from PMC servo LISO_compare.pngPMC_TF_2.pngPMC_TF.m.zippmc_data.matpmc.fil.zip
    Reply  Wed Nov 3 02:08:06 2010, Koji, Notes, PMC, TF from PMC servo 
       Reply  Wed Nov 3 15:38:05 2010, tara, Notes, PMC, TF from PMC servo mod_TF.pngmisnomber.png
          Reply  Thu Nov 4 04:13:59 2010, Koji, Notes, PMC, TF from PMC servo 
             Reply  Thu Nov 4 21:13:32 2010, tara, Notes, PMC, TF from PMC servo compare_TF1.pngcompare_TF.png
Message ID: 379     Entry time: Wed Nov 3 01:22:57 2010     Reply to this: 380
Author: tara 
Type: Notes 
Category: PMC 
Subject: TF from PMC servo 

I determined the OLG TF of the whole PMC loop, and TFs from servo paths and optical path.

 

We want to modify the PMC servo to optimize the PMC loop, so we have to know what are the TFs from part where we can modify,

and where we can't (optical path).

 

The whole TF is measured before, but I remeasured again just to make sure that there won't be any problem from the laser.

How I measure the whole TF is [here].

 

 I measured the OLG TF from the PMC servo.

The results agree well with the LISO model, see fig 1.

The pole (in LISO model)around 100kHz comes from non ideal behavior of PA85.

When I switch to ideal opamp model, the response is flat.

 

Then,

 Optical TF = Whole TF - Servo TF.

The Optical TF won't be modified. It will be used to compute the whole TF after the PMC servo modification. 

The measurement at low frequency does not look nice because the signal was suppressed by the gain.

But the TF around UGF still looks fine to work with.

Attachment 1: LISO_compare.png  34 kB  Uploaded Wed Nov 3 02:31:16 2010  | Hide | Hide all
LISO_compare.png
Attachment 2: PMC_TF_2.png  41 kB  Uploaded Wed Nov 3 02:31:38 2010  | Hide | Hide all
PMC_TF_2.png
Attachment 3: PMC_TF.m.zip  1 kB  Uploaded Wed Nov 3 02:32:25 2010
Attachment 4: pmc_data.mat  118 kB  Uploaded Wed Nov 3 02:32:34 2010
Attachment 5: pmc.fil.zip  1 kB  Uploaded Wed Nov 3 02:39:04 2010
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