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Tue May 14 01:56:20 2013, Jenne, Update, Green Locking, Xend Green tweaked
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Tue May 14 02:19:13 2013, Koji, Update, Green Locking, Xend Green tweaked
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Tue May 21 18:18:23 2013, Manasa, Update, Green Locking, Xend Green aligned
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Tue May 21 23:29:57 2013, Manasa, Update, Green Locking, Xend Green aligned
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Tue May 28 19:35:17 2013, Manasa, Update, Green Locking, Still searching for the X green beat note
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Thu May 30 01:02:41 2013, Manasa, Update, Green Locking, Found it! 
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Mon Jun 3 21:09:55 2013, Manasa, Update, Green Locking, X green beatnote through beatbox
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Tue Jun 11 22:16:56 2013, Manasa, Summary, Green Locking, ALS for X arm
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Thu Jun 13 22:31:12 2013, Manasa, Summary, Green Locking, X arm ALS 
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Fri Jun 14 07:06:19 2013, Koji, Summary, Green Locking, X arm ALS
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Message ID: 8653
Entry time: Thu May 30 01:02:41 2013
In reply to: 8651
Reply to this: 8666
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Author: |
Manasa |
Type: |
Update |
Category: |
Green Locking |
Subject: |
Found it! |
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X green beat note found!
Key points
1. Near-field and far-field alignment on the PSL table. The near-field alignment checked by looking at the camera and the far-field alignment checked by allowing the beams to propagate by removing the DC PD.
2. Check laser temperature and get a sense of how the offset translates to the actual laser temperature.
3. Get an idea of the expected temperature of laser using the plot in elog.
Data
PSL laser temperature = 31.45 deg C
X end laser temperature = 39.24 deg C
C1-ALS-X_SLOW_SEERVO2_OFFSET = 4810
Amplitude of beat note = -40dBm
I do not understand why
1. The amplitude of beatnote falls linearly with frequency (peak traced using 'hold' option of the spectrum analyzer).
2. I found the beat note at the RF output of the PD. Earlier, while I was trying to search for the beatnote from the RFmon output of the betabox, there was a strong peak at 29.6MHz that existed even when the green shutters were closed. It's source has to be traced.
Next
Solve beatbox puzzle and lock arm using ALS.
 
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