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Sun Feb 3 13:20:02 2013, Koji, Summary, General, Hypothesis 
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Mon Feb 4 10:45:51 2013, Jamie, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Mon Feb 4 11:10:59 2013, Koji, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Mon Feb 4 19:33:19 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Tue Feb 5 02:04:44 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Tue Feb 5 03:16:51 2013, Koji, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Tue Feb 5 10:09:08 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Tue Feb 5 11:30:19 2013, Koji, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Wed Feb 13 01:26:08 2013, yuta, Summary, General, rough analysis of aligned PRM-PR2 mode scan
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Wed Feb 6 15:20:55 2013, yuta, Summary, General, FWHM was wrong
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Mon Feb 4 15:06:56 2013, Koji, Summary, General, Hypothesis
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Mon Feb 4 19:48:32 2013, Jamie, Summary, General, arbcav recalc of PRC with correct ITM transmission 
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Message ID: 7994
Entry time: Mon Feb 4 19:33:19 2013
In reply to: 7991
Reply to this: 7997
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Author: |
yuta |
Type: |
Summary |
Category: |
General |
Subject: |
rough analysis of aligned PRM-PR2 mode scan |
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[Jenne, Yuta]
We redid PRM-PR2 cavity scan because last one (elog #7990) was taken with the sampling frequency of 2 KHz. We have also done TMS measurement.
Method:
1. Align input TTs and PRM to align PRM-PR2 cavity.
2. Sweep cavity length using C1:SUS-PRM_LSC_EXC.
3. Get data using Jamie's getdata and fitted peaks using /users/jrollins/modescan/prc-pr2_aligned/run.py
4. Calculated cavity parameters
Results:
Below is the figure containing peaks used to do the calculation.

From 11 MHz sidebands, calibration factor is 462 +/- 22 MHz/sec (supposing linear scan around peaks)
FWHM is 1.45 +/- 0.03 MHz.
TMS is 2.64 +/- 0.05 MHz.
Error bars are statistical errors of the average over 3 TEM00 peaks.
If we believe cavity length L to be 1.91 m, FSR is 78.5 MHz.
So, Finesse will be 54 +/- 1 and cavity g-factor will be 0.9944 +/- 0.0002. 0.9889 +/- 0.0004 (Edited by YM; see elog #8056)
If we believe RoC of PRM is exactly +122.1 m, measured g-factor insists RoC of PR2 to be -187 +/- 4.
If we believe RoC of PR2 is exactly -600 m, measured g-factor insists RoC of PRM to be 218 +/- 6.
Discussion:
1. Finesse is too small (expected to be ~100). This time, data was taken 16 KHz. Cut-off frequency of the digital antialiasing filter is ~ 5 kHz (see /opt/rtcds/rtscore/release/src/fe/controller.c ). FWHM is about 0.003 sec, so it should not effect much according to my simulation.
2. I don't know why FWHM measurement from the last one is similar to this one. The last one was taken 2 KHz, this means anti-aliasing filter of 600 Hz. This should double FWHM.
3. Oscilloscope measurement may clear anti-aliasing suspicion. |