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Entry  Mon Apr 28 11:03:57 2014, Koji, Configuration, LSC, New ALS servo implemented for the X arm 
    Reply  Tue Apr 29 01:10:16 2014, Koji, Configuration, LSC, New ALS servo implemented for the X arm ALSX_SPE.pdfALSX_PDH_SPE.pdf
Message ID: 9874     Entry time: Tue Apr 29 01:10:16 2014     In reply to: 9866
Author: Koji 
Type: Configuration 
Category: LSC 
Subject: New ALS servo implemented for the X arm 

New ALS servo performance

Attachment 1:

Comparison between the old (orange) and new (red). The new error signal (red) is suppressed like a white noise as expected.

Comparison between the out-of-loop evaluation (black) and the in-loop signal (red). Below 50Hz the out-of-loop is limited by the sensor-noise like something.
This out-of-loop stability was measured with the ALS stayed at the top of the resonance and calibrated the POX11 error signal.

Attachment 2:

New ALS servo with the LSC PDH signal. When the PDH signal is used for the control, FM4 is additionally used.
In this condition, the error signal was measured and calibrated into frequncy noise (Hz/sqrtHz).

By comparing the POX (with the new servo) and POY (with the old servo) signals, one can see that the new servo has better supression below 30Hz with almost no cost at ~100Hz.

Attachment 1: ALSX_SPE.pdf  199 kB  | Hide | Hide all
ALSX_SPE.pdf
Attachment 2: ALSX_PDH_SPE.pdf  143 kB  | Hide | Hide all
ALSX_PDH_SPE.pdf
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