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Entry  Thu Jun 14 21:37:37 2012, yuta, Update, Green Locking, succeeded in 1FSR mode scan YarmScan20120614.png
    Reply  Fri Jun 15 00:50:54 2012, yuta, Update, Green Locking, scanned Y arm for 5FSR YarmScan20120614_2.png
       Reply  Fri Jun 15 01:53:05 2012, Koji, Update, Green Locking, scanned Y arm for 5FSR 
          Reply  Sat Jun 16 12:03:41 2012, Zach, Update, Green Locking, scanned Y arm for 5FSR 
             Reply  Sat Jun 16 13:01:17 2012, yuta, Update, Green Locking, scanned Y arm for 5FSR YarmScanDV.png
       Reply  Sat Jun 16 18:17:00 2012, yuta, Update, Green Locking, Y arm length using 5FSR scan ALS-BEATY_COARSE_I_IN1_DQ.pngCalibYarmScan20120614_2.png
          Reply  Sat Jun 16 18:51:44 2012, Koji, Update, Green Locking, Y arm length using 5FSR scan 
             Reply  Sat Jun 16 19:32:11 2012, yuta, Update, Green Locking, Y arm length using 5FSR scan 
Message ID: 6819     Entry time: Fri Jun 15 00:50:54 2012     In reply to: 6818     Reply to this: 6820   6825
Author: yuta 
Type: Update 
Category: Green Locking 
Subject: scanned Y arm for 5FSR 

I scanned Y arm for 5FSR (below).
I could done this after I put a whitening filter.
Currently, whitening filter between the beatbox and AA filter is made of

  Ponoma blue box(passive filter with zero at 1 Hz, pole at 10 Hz) + SR560(flat gain 100)

I couldn't do more than 5FSR because SR560 overloads. I checked it by staring at the indicator during the scan.
Reason why we kept loosing lock last night was the overload of  SR560. Mystery solved!

Anyway, 5FSR is enough.
Our next step is to reduce residual arm length fluctuation.

YarmScan20120614_2.png


Also, I increased the alingnment of IR. So, the higher order modes are less than the last scan.

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