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40m Log |
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Fri Apr 18 20:17:17 2014, Jenne, Update, LSC, ALS noisy 
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Mon Apr 21 22:53:16 2014, manasa, Update, LSC, ALS noise 
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Tue Apr 22 01:11:42 2014, Jenne, Update, LSC, TRY 60Hz noise
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Tue Apr 22 21:54:50 2014, manasa, Update, LSC, TRY 60Hz noise
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Tue Apr 22 22:49:10 2014, rana, Update, LSC, TRY 60Hz noise
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Wed Apr 23 19:58:00 2014, manasa, Update, LSC, TRY 60Hz noise
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Tue May 6 18:32:14 2014, steve, Update, LSC, TRY 60Hz noise hunt
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Wed May 7 14:01:36 2014, steve, Update, LSC, TRY 60Hz noise hunt
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Thu May 8 17:25:17 2014, steve, Update, LSC, TRY 60Hz noise hunt
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Fri May 16 16:08:12 2014, steve, Update, LSC, Isolating base plates
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Wed Apr 23 23:48:30 2014, manasa, Update, LSC, Y end whitening board  
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Thu Apr 24 14:23:09 2014, not manasa, Update, LSC, Y end whitening board
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Thu Apr 24 23:55:31 2014, Koji, Update, LSC, Y end whitening board
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Fri Apr 25 10:43:57 2014, Koji, Update, LSC, (Fixed) Y end whitening board   
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Thu Dec 11 18:12:46 2014, ericq, Update, LSC, (Fixed) Y end whitening board
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Thu Dec 11 22:44:23 2014, rana, Update, LSC, QPD screens
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Thu Apr 24 00:11:35 2014, Jenne, Update, LSC, Yend shutter back.
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Sun Apr 27 20:26:19 2014, Koji, Update, LSC, Phase Tracker servo characterization 
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Sun Apr 27 21:30:59 2014, Koji, Update, LSC, ALS servo characterization 
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Mon Apr 28 10:24:10 2014, Koji, Update, LSC, error signal characterization 
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Mon Apr 28 10:34:51 2014, Koji, Update, LSC, new ALS servo design 
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Mon Apr 28 10:48:48 2014, Koji, Update, LSC, new ALS servo design: comparison 
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Mon Apr 28 10:59:54 2014, Koji, Update, LSC, New ALS servo design: expected error signals 
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Mon Apr 28 11:08:11 2014, Koji, Update, LSC, New ALS servo design: expected error signals
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Message ID: 9862
Entry time: Mon Apr 28 10:24:10 2014
In reply to: 9861
Reply to this: 9863
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Author: |
Koji |
Type: |
Update |
Category: |
LSC |
Subject: |
error signal characterization |
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As we now have the loop model, we can characterize the error signals.
We have the following data:
1) Free-running ALS error signals (i.e. phase tracker output) calibrated in Hz (for 532nm) (blue)
2) Controlled ALS error signals calibrated in Hz (for 532nm) (red)
3) ALS error signals measured with X and Y arm locked with the IR PDH. (black)
This is likely to represent the sensing noise of the beatnote detection
from 2) we can derive the similar quantity as 1)
4) Estimated free-running ALS error signals from the controlled signals (green)
Remarks:
- From 1) and 4) we can see that the phase tracker is not perfectly linear. It seems that fast fringing of the phase tracker is causing upconversion.
- From 2) and 3) the servo loops don't have enough gain between 3Hz and 20Hz. On the other hand they have too much gain bekow 3Hz. |
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