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Fri Feb 14 17:40:27 2020, anchal, DailyProgress, ISS, Installed ISS on both paths using SR560s 
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Sat Feb 15 18:57:43 2020, rana, DailyProgress, ISS, Installed ISS on both paths using SR560s
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Thu Feb 20 17:42:23 2020, rana, DailyProgress, ISS, Installed New ISS on both paths using SR560s
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Sun Feb 23 18:19:32 2020, rana, DailyProgress, ISS, Installed New ISS on both paths using SR560s
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Fri Feb 28 14:00:11 2020, anchal, DailyProgress, ISS, Installed New ISS on both paths using SR560s - PROBLEM
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Sun Mar 1 16:34:31 2020, rana, DailyProgress, ISS, Installed New ISS on both paths using SR560s - PROBLEM
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Mon Mar 2 16:48:12 2020, anchal, DailyProgress, ISS, Follow-up, porbalem stopped happening, OLTF plot.
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Message ID: 2538
Entry time: Fri Feb 14 17:40:27 2020
Reply to this: 2539
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Author: |
anchal |
Type: |
DailyProgress |
Category: |
ISS |
Subject: |
Installed ISS on both paths using SR560s |
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I've installed ISS on both paths using 3 SR560s each. Preliminary feedback is setup to get a stable loop. More optimization with TF analysis can be done further.

Path changes:
- I replaced the unmarked waveplate in the north path right after the EOAM at (112, 39) with a zeroth-order quarter waveplate.
- I adjusted these quarter waveplates at (112, 39) and (90, 24) to the half transmission through the PBS when EOAM inputs are shorted.
- I followed the notes in Antonio's post (See CTN:1593 and CTN:1604).
ISS:
- ISS is formed with three SR560s in series.
- First SR560 is AC coupled, has a 2nd order zero at 1 Hz and gain of 100 at Low noise Mode.
- The second SR560 is DC coupled and has a pole at 1 kHz (North) and 3 kHz (South) with gain 1 and High Dynamic Reserve setting.
- The third SR560 is also DC coupled and has a pole at 300 kHz with gain 1 and High Dynamic Reserve setting.
Measurement:
- I took the measurement of the spectrum from the output of transmission photodiodes.
- I used the calibrated coupling factor I measured earlier to convert the measured voltage to watts of power right after the cavities. (See CTN:2528).
- Measurement configuration files is attached.
- We see about a factor of 10 improvement in the intensity noise between 100Hz to 1 kHz.
- Note that the bad spikes notes in the beatnote spectrum at 480 Hz and around 900 Hz are present in the north transmission spectrum as well.
- Effect on the beatnote noise would be evident after tonight's measurement at 3 am. In my preliminary measurements, I see some reduction in noise below 200 Hz but nothing much.
Data |
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