J. Kissel, F. Matichard, P.Fristchel
After putting together information from all over the everywhere, I've produced (dare I call it) a NoiseBudget for the H2 OAT Y Arm cavity. Attached are the results.
[[Editorial Note: I've uploaded -v2 of the plots. Now the calibration for the cavity length signal is just 1e-9 [m/nm], as Matt suggests in his comments below. Also removed the free-running laser frequency noise from SARM L budget since it's not applicable when the PLL is on, and corrected the ylabel typo on the Pitch estimate, so it now reads [rad/rtHz] as expected.]]
All data was measured starting at 2012-07-17 04:50UTC (7 averages, BW 0.005, 50% overlap), which we believe is the second stretch of cavity lock shown in LHO aLOG 3463.
Captions (labeled by page number):
(1) The Money Plot, showing the my predicted cavity length against the directly measured cavity length, in [m/rtHz]
(2) A similar model of the cavity pitch, but still a prediction without a measurement that directly confirms it
[[The remaining plots are merely for support of the first two:]]
(3 - 5) For ITMY, individual NoiseBudget breakdown of test mass motion degree of freedom used in the model (L, V, and P)
(6 - 8) For ETMY, individual NoiseBudget breakdown of test mass motion degree of freedom used in the model (L, V, and P)
(9) A comparison between the BSC-ISI's input spectra for Y (projected to L in the model), and RX (projected to P in the model)
(10 - 11) For ITMY and ETMY respectively, the contribution of every degree of freedom input to pitch of the test mass
(12 - 13) Directly measured spectra of BSC8- and BSC6-ISI's ST2 GS-13s,
(14 - 15) Model transer function between all DOFs at the SUS point and the test mass.
Calibration Details:
ISI ST2 GS13s
- Channels: H2:ISI-$(OPTIC)_ST2_DAMP_$(DOF)_IN1_DQ
- Input filter calibration: ON (creates an ideal 1 Hz geophone, that asymptotes to 1 [(nm/s) / ct] at high frequency)
- DTT: (Based on LHO aLOG 3458)
units: [m]
gain: 1.59e-10 [m/ct] (1e-9 [m/nm] * 1/(2pi) [rad / (rad/s)])
poles: 0,0,0
zeros: 0.7 0.7
(I gathered/plotted/calibrated the data in DTT for sanity check, then exported the data, uncalibrated, to Matlab)
- Matlab:
Used production calibration file:
$(SeiSVN)/seismic/BSC-ISI/Common/Calibration_BSC_ISI/aLIGO/aLIGO_BSC_ISI_Calibration.mat
code snippet:
isiCalibration = load(bscCalibFile);
gs13Model_nm = abs(squeeze(freqresp(isiCalibration.GS13_Model,2*pi*freq)));
rawData = load(bscDataFile);
rawFreq = rawData(:,1);
for iChan = 2:size(rawData,2)
interpData(iChan,:) = interp1(rawFreq,rawData(:,iChan),freq);
end
for iDOF = 1:6
% X Y RZ Z RX RY
bscData(1).ST2.CART(iDOF,:) = interpData(iDOF+1,:) ./ abs(gs13Model_nm' * 1e9);
bscData(2).ST2.CART(iDOF,:) = interpData(iDOF+7,:) ./ abs(gs13Model_nm' * 1e9);
end
Cavity Length Signal
- Channel: H2:SUS-ETMY_M0_LOCK_L_IN1_DQ (which is the control signal from the VCO FMON [[I think]], but passed directly to the M0 TOP stage of the QUAD)
- DTT: (Based on LHO aLOG 3482)
units: [m]
gain: 1e-9 [m/nm]
poles: (none)
zeros: (none)
- Matlab: (Based on above)
code snippet:
% H2:SUS-ETMY_M0_LOCK_L_IN1_DAQ is already calibrated into [nm], so we just
% need to multiply by 1e-9 [m/nm]
cavityData = interpData(14,:) .* 1e-9; % [m]
Data collection details:
The original data collection .xml can be found here:
$(SusSVN)/sus/trunk/Common/Data/2012-07-17_H2OAT_ASDs.xml
which has been exported to
$(SusSVN)/sus/trunk/Common/Data/2012-07-17_H2OAT_ASDs.txt
Model script: $(SusSVN)/sus/trunk/QUAD/Common/MatlabTools/plotsinglearmmotion.m
