anamaria.effler@LIGO.ORG - posted 18:37, Tuesday 10 January 2012 - last comment - 08:12, Wednesday 11 January 2012(2011)
FMY Transfer Function Results from last night
Last night we took FMY and ITMY TFs, but we didn't get to finish the reaction chain measurement because morning came. I am repeating that tonight, after Vincent is done with the BSC ISI. Attached are the FMY transfer functions, compared with the new model tweaked by JeffK. All looks great except pitch is a bit off. I will check how it looks compared to the other measurements tomorrow. JeffG will post the results for ITMY main chain, and we'll do the same for R0 once we get the data.
Non-image files attached to this report
Comments related to this report
I agree, the results look fantastic. My guess is that the only discrepancy between model and measurement seen (Pitch2Pitch TF, pg 5 of attachment) is due to a variation in M1 blade-spring tip heights (and therefore suspension breakoff point d1). As we've mentioned many times before, these heights are set by-eye to the roughly +/- 1mm precision, and the magnitude of that particular transfer function is sensitive to such levels of precision. Given this data we should consider the H2 SUS FMY mechanical dynamics accepted, and should be used as the reference data for this suspension for all future measurements. However, we're still fighting confusion over loop signs, so we can't yet accept the control system. Note -- this doesn't mean we're done with taking this particular measurement for all time -- it should be performed any time the mechanical system (specifically the suspended components, and/or its sensors and or actuators) is changed. This includes after an earthquake stop lock/unlock cycle.