Finally I overcame difficulties with adapting Sonia's Matlab programs for XARM (Sonia's program was for MC),
and now there exists a Matlab program that makes a fit of a ringdown curve and calculates Q-factor for a mirror ITMX.
Specifically, this program allows to measure ringdown, fit it and calculate Q-factor for the ITMX-mirror for a specific value of
"C1:SUS-ITMX_SUSPOS_GAIN".
Attached is a plot of a ringdown curve and its fit for the value 4.0 in channel "C1:SUS-ITMX_SUSPOS_GAIN".
Calculations yield the result Q=3.7+-0.2 for the value 4.0 in channel "C1:SUS-ITMX_SUSPOS_GAIN".
As Robert started 10 minutes ago the long procedure of the whole interferometer locking,
I cannot disturb the interferometer now, so I will measure Q-factors for various combinations of suspension damping gain on Tuesday.
I will also easily modify the program for measuring Q-factors of ETMX-mirror and make measurements with ETMX on Tuesday.
The Matlab scripts are in directory /cvs/cds/caltech/users/rodionov/Q-Factors/ |