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 Tue May 26 02:15:36 2020, gautam, Update, LSC, Lock acquisition portal entry
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 Tue May 26 02:31:00 2020, gautam, Update, LSC, Lock acquisition sequence 
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Wed May 27 20:14:51 2020, Koji, Update, LSC, Lock acquisition sequence
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Tue May 26 02:37:19 2020, gautam, Update, LSC, DARM loop measurement and fitting
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Tue May 26 03:01:35 2020, gautam, Update, LSC, CARM loop
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Wed Jun 3 01:46:14 2020, gautam, Update, LSC, CARM loop
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Tue May 26 03:06:59 2020, gautam, Update, LSC, PRFPMI sensing matrix
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Tue May 26 03:26:58 2020, gautam, Update, LSC, Preliminary noise budget
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Tue May 26 14:32:44 2020, gautam, Update, LSC, Arm transmission RIN
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Wed May 27 19:36:33 2020, Koji, Update, LSC, Arm transmission RIN
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Thu May 28 18:36:45 2020, gautam, Update, LSC, Arm transmission RIN
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Fri May 29 00:34:57 2020, rana, Update, LSC, Arm transmission RIN
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Wed Jun 3 02:14:32 2020, gautam, Update, ASC, PRC ASC improves arm transmission RIN
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Fri Jun 19 16:30:09 2020, gautam, Update, ASC, Some thoughts about ASC
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Tue Jul 7 14:06:10 2020, gautam, Update, ASC, Some more thoughts about ASC
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Tue May 26 16:00:06 2020, gautam, Update, LSC, Power buildup diagnostics
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Wed May 27 17:41:57 2020, Koji, Update, LSC, Power buildup diagnostics
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Wed Jun 3 02:08:00 2020, gautam, Update, LSC, Power buildup diagnostics
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Wed Jun 3 01:34:53 2020, gautam, Update, LSC, Lock acquisition update portal
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Wed Jun 3 03:29:26 2020, Koji, Update, LSC, Lock acquisition update portal
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Wed Jun 3 11:40:56 2020, gautam, Update, LSC, Lock acquisition update portal
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Wed Jun 3 18:49:47 2020, gautam, Update, LSC, PRG and CARM signal sign
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Message ID: 15355
Entry time: Tue May 26 14:32:44 2020
In reply to: 15348
Reply to this: 15359
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| Author: |
gautam |
| Type: |
Update |
| Category: |
LSC |
| Subject: |
Arm transmission RIN |
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Summary:
The measured RIN of the arm cavity transmission when the PRFPMI is locked is ~10x in RMS relative to the single arm POX/POY lock. It is not yet clear to me where the excess is coming from.
Details:
Attachment #1 shows the comparison.
- For the PRFPMI lock, the ITM Oplev Servos are DC coupled, and the ETM QPD ASC servos are also enabled.
- Admittedly, the PD used in the POX/POY lock case is the Thorlabs PD while when the PRFPMI is locked, it is the QPD.
- I found that there isn't really a big difference in the RIN if we normalize by the IMC transmission or not (this is what the "un-normalized" in the plot legend is referring to). A scatter plot of TRX vs TRY and TRX/MCtrans vs TRY/MCtrans have nearly identical principal components.
- To convert to RIN, I divided the ocmputed spectra by the mean value of the data stream. For the POX/POY lock, the arm transmission is normalized to 1, so no further manipulation is required.
- The spectra are truncated to 512 Hz because the IMC sum channel is DQ-ed at 1 kHz, but because of the above bullet point, in principle, I could calculate this out to higher frequencies.
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