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Tue Aug 12 21:38:19 2008, John, Update, LSC, Accidental higher order mode resonances in the arms
Tue Oct 28 11:10:18 2008, Alberto, Update, LSC, Higher Order Mode resonances in the X arms
Tue Oct 28 11:10:18 2008
In reply to:
Higher Order Mode resonances in the X arms
Recently we had been having some trouble locking the full IFO in the
configuration (SRC on
It was thought that an accidental higher order mode resonance in the arms may have been causing problems.
I previously calculated the locations of the resonances using rough arm cavity parameters(
). Thanks to Koji
and Alberto I have been able to update this work with measured arm length and g factors for the y arm (
I have also included the splitting of the modes caused by the astigmatic ETM. Code is attached.
I don't see any evidence of
resonances in the y arm.
In the attached plot different colours denote different frequencies
The numbers above each line are the mn of TEMmn.
Solid black line is the carrier resonance.
I plugged the measures of the length of the X arm and radius of curvature of ETMX I made in to John's code to estimate the position of the resonances of the HOM for the sidebands in the X arm. Here's the resulting plot.