After fixing up my calculations in my scripts, I have calculated the final PRMI sensing matrix (as measured very close to the violin frequency, so things may not be perfect). The data is from the file that Koji mentioned in his elog when he did the measurement: elog 8611, sensematPRM_2013-05-22.12615.dat
Sensing Matrix, units = cts/meter, phase in degrees
PRCL Mag PRCL Phase MICH Mag MICH Phase
AS55 1.064E+09 141.880 3.442E+09 11.929
REFL11 3.474E+13 -108.372 4.316E+11 106.143
REFL33 3.242E+11 -90.392 1.080E+10 81.037
REFL55 3.373E+11 -92.060 1.394E+10 15.153

In the plot, the little blobs on the ends of the 'sticks' are the error blobs. Many of them are smaller than is really visible - this is good. These errors come from measuring the lockin outputs several times while there is no drive to any optics, then the errors are propagated to each degree of freedom. These errors do not incorporate any information about the precision of the actuator calibration, and they assume that the shape of all the sensor transfer functions are the same.
If you look at the REFL11 and REFL33, it kind of seems like a miracle that we've ever been able to lock the full PRMI with the I&Q signals from either PD! |