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
The output of PDH_FMON, and ISC input to the ETM, is already calibrated in nm. That, this part:
cavityModel_m.gain = 6.1e-10; % [m/ct] cavityModel_m.poles_Hz = [1.6 10 10]; cavityModel_m.zeros_Hz = [40 100 100]; Is already in the PDH_FMON filter bank.