J. Kissel, T. Sadecki,

There will be lots more details to come in the comments, but in short:
    - On Monday, I completed what I can of the in-air measurements of the remaining three fibers (where Travis graciously takes care of switching the shadow sensor setup between measurements), that had started on Friday (see starter aLOG LHO:57621 for details of setup and method.)
    - I was able to measure the Fundamentals (~500 Hz), and the 3rd, 4th, and 5th harmonics (~1.5 kHz, ~2.0 kHz, and ~2.5 kHz) for all four fibers. They are inconsistent with predictions from both first principles calculation and finite-element analysis. As before, the modes are anharmonic, loosing about 25 Hz per harmonic.
    - I was NOT able to measure the 2nd harmonic for ANY of the fibers -- these modes just did not show up, narrow-band searching across a wide band range of frequency, with many different excitation types.
    - I had *much* more success with the SR785's CHIRP style excitation waveform rather than the Band-limited White Noise (BLN) that has been used for years. I also played with the window function used for the FFT which helped further understanding of the myriad of data artifacts (no window for the BLN, Blackman Harris for the CHIRP).

Here's a summary table.
Global    Local  S/N         FPC (Hz)   FEA (Hz)    Fun. (Hz)    2nd (Hz)    3rd (Hz)    4th (Hz)    5th (Hz)
-X / +Y   FL     S1800721    494.0      495.25      501.375      988???      1465.250    1930???     2392.125
+X / +Y   FR     S1800751    496.9      497.31      508.125      951???      1484.500    1953.000    2413.500    
-X / -Y   BR     S1800649    496.0      497.01      507.625      n.f.        1481.375    1947.25     2405.88   (EMS)
-X / -Y   BL     S1800746    494.9      495.89      507.750      n.f.        1448.475    1953???     n.f.

where 
    - Global = the location of the fiber w.r.t. to the installed center of mass of ITMY, in IFO global coordinates
    - Local = [FL, FR, BR, BL] = front or back, and left or right, where the front is HR surface of ITMY (i.e. +Longitudinal), and left is on the left as you look from the back of the suspension (in this case, down the yarm; i.e. +Transverse)  
    - S/N = fiber serial number
    - FPC = first principles calculation (based on fiber profiling data), 
    - FEA = finite element analysis (also based on fiber profiling data), 
    - Fun. = fundamental frequency as measured by this in-air shadow sensor technique, with accuracy of 0.125
    - 2nd, 3rd, 4th, 5th = the second (~1kHz)
    - n.f. = not found
    - "???" = there might be something there, but the data and answer is questionable.
    - EMS = evidence of the expected mode splitting (from the two DOFs of resonance), seen especially at higher harmonics

I note the uncertainty in the shadow sensor data is +/- 0.125 Hz, defined by the frequency resolution of the data, measured with 400 "lines" (frequency points) over a 50 Hz span. For *some* of the modes, I had enough time to gather 400 lines over 6.25 Hz span (i.e. a 0.015 Hz resolution), but the Q's of the modes are low enough (or the mode frequency was broadened enough for whatever other reason) that measuring at a 0.125 Hz resolution is good enough and/or measuring at 0.015 Hz doesn't get you any more precise of an answer.

Plots and details to come.