J. Kissel, T. Vo

Now that we're sure we completely understand the calibration of the two optical levers, I've installed Thomas' calibration in the gain field of the $(IFO):SUS-$(OPTIC)_L3_OPLEV_[PIT/YAW] filter banks. The resulting calibrated spectra are attached.

Several things to note:

- After proper whitening, I believe that the ITMY optical lever is measuring real motion out to the limit of the spectra I show (hundred of Hz).
- I think the "real" motion, above ~5 Hz is dominated by structural resonances of the lever launcher/receiver, and probably other various not-test-mass-motion things.
- The low-frequency (< 5 Hz) motion of the ITM (in both Pitch and Yaw) is just about what has been predicted / measured by other independent methods.
- ETMY *does not* have his whitening control board installed yet, so there's no whitening on the signal and is hence dominated by ADC noise, especially in Yaw.
- The ETM Pitch spectra looks also roughly at the amplitude expected, and similar to the ITM Pitch spectra, but 
- The ETM Yaw signal appears orders of magnitude below ETM Pitch, as well as ITM Yaw, assuming the only feature in the spectra (at 0.43 Hz) is real motion. Why? The spot needs centering, that's all -- it currently shows it's off in the weeds somewhere mrads away from center.


Tomorrow: 
- Center the spot on the ETM QPD
- Install whitening control board, explore parameters a bit (just to see if it's different from ITMY -- my guess is that it won't be)
- Remeasure.

Almost there....

P.S. For future reference, once the calibration is installed (which it is now for H2 ITMY and H2 ETMY), the following channels are calibrated into microradians:

$(IFO):SUS-$(OPTIC)_L3_OPLEV_PIT_OUT_DQ
$(IFO):SUS-$(OPTIC)_L3_OPLEV_YAW_OUT_DQ