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H1 ISC
elenna.capote@LIGO.ORG - posted 17:05, Friday 08 April 2022 - last comment - 17:10, Friday 08 April 2022(62531)
OMC Scans Single Bounce 8 April 2022

Craig, Elenna

OMC_ASC was off during these scans

Single bounce with ITMX

We used the template from userapps omc/h1/templates/OMC_scan_50W.xml, however we weren't able to save a new template for some reason we don't understand.

Scan GPS time Input Power (W) RF9 mod depth (dBm) RF45 mod depth (dBm) Notes
1 1333493018 10 23.4 27 dark offsets wonky
2 1333493342 10 23.4 27 dark offsets wonky
3 1333405229 10 23.4 27 scan cut off early, something odd happened
4 1333495933 10 23.4 27 more wonky results, PZT2 offset too high, only scanned half the range
5 1333496192 10 23.4 27 finally a good scan!

The dark offsets during the first two scans made some of the results negative so Craig adjusted the offsets and rescanned. Scans 3 and 4 the PZT2 offset was too high and the scans only swept half the range.

We reduced the power to 2 W and realigned the test masses for TCS tests. OMC left in down.

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craig.cahillane@LIGO.ORG - 17:10, Friday 08 April 2022 (62533)
Link 

Here is the single bounce OMC scan we took with 10W input.
We scanned over one full FSR and saw two carrier peaks (second plot)

More analysis coming (We'll use this to measure our modulation depths).
We are clearly missing the peaks when we calibrate using the OMC FSR = 264.8 due to the PZT nonlinearity.  (first plot)
We'll calibrate using the 9.1 MHz peaks to get a better local calibration of the OMC length.

Code is in https://git.ligo.org/aligo_commissioning/labutils/-/tree/master/omc_scan,
made with plot_omc_scan_single_bounce_nds2.py.
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