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Entry  Wed Sep 11 23:34:37 2013, Masayuki, Summary, Green Locking, ALS locking in both arms noise.pdf
    Reply  Wed Sep 11 23:43:10 2013, Koji, Summary, Green Locking, ALS locking in both arms 
       Reply  Thu Sep 12 00:07:26 2013, Masayuki, Summary, Green Locking, ALS locking in both arms 
Message ID: 9123     Entry time: Wed Sep 11 23:34:37 2013     Reply to this: 9124
Author: Masayuki 
Type: Summary 
Category: Green Locking 
Subject: ALS locking in both arms 

[manasa, masayuki]

We locked the XARM and YARM with using ALS control loop and we succeeded to lock stably both arms. The performance of the ALS was tested with a measurement of the calibrated error signal. (attachment 1)

- red and blue : the in-loop noise of ALS of each arm.

- green and purple:Stability of the beat-note frequency with the MC and the arm freely running.

Discussion

In the high frequency region, YARM has larger noise than XARM, and these noises were not there in previous measurements by Koji and Manasa (elog8865). You can see that in both of in-loop noise and free running noise. These noises may be caused by the Green PDH servo or hte phase tracker servo or any other electrical staff. We will start noise budget of these servo.

At higher frequency than UGF of ASL control loop, the loop does not suppress the noises at all, but the inloop and free running noise are not equivalent. I have no idea about that so far.

 

 

 

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