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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: 381     Entry time: Wed Nov 3 15:38:05 2010     In reply to: 380     Reply to this: 382
Author: tara 
Type: Notes 
Category: PMC 
Subject: TF from PMC servo 

Sorry for the confusion, PZT actuator is included in the optical TF. 

The plot on fig2 below shows the TF of PZT part, offset by 1 dB to match the misnomer optical path TF.

Thus, the real optical TF is rather flat with magnitude~ 1 dB, the phase shift is 180 degree,

 and the modifiable TF (LISO model) is plot on fig1. This plot has not taken the gain from the slider into account yet.

Quote:

Incomprehensible.

Why is the optical TF not (kinda) flat?

Why does the PZT actuator completely ignored?

You need to talk to me tomorrow afternoon when I am in ATF.

Quote:

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.

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: mod_TF.png  22 kB  Uploaded Wed Nov 3 16:55:46 2010  | Hide | Hide all
mod_TF.png
Attachment 2: misnomber.png  26 kB  Uploaded Thu Nov 4 00:29:24 2010  | Hide | Hide all
misnomber.png
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