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CAL (General)
wataru.ogaki - 12:45 Tuesday 26 November 2019 (11754) Print this report
measurements for propagation of actuator efficiency
This early morning I performed actuator efficiencies calibration by propagating them from BS to ETMY.


==temperature==
BS: 296K
ITMY: 242K
ETMY: 246K


==MICH optical gain== (pic.1)
MICH optical gain was measured by free swinging Michelson under simple MICH configuration (both ETMs are misaligned).
contrast: 91.0%
MICH optical gain (=C_MICH) : 9.12e9[cnt/m]


==MICH TF== (pic.2)
under simple MICH lock
C_MICH * A_BS = MICH1_IN1 / MICH2_OUT ...(1)


==BS actuator efficiency==
MICH input matrix gain : 0.0002
A_BS = (1) / (C_MICH * 0.0002) = 6.02e-11/f^2 [m/cnt] (@1Hz)


==BS to ITMY== (pic.3)
C_MICH * A_BS / (1+G_MICH) = MICH1_IN1 / BS_ISCINF_L_EXC ...(2)
C_MICH * A_ITMY / (1+G_MICH) = MICH1_IN1 / ITMY_ISCINF_L_EXC ...(3)
A_ITMY / A_BS = (3) / (2) ~ 0.0284
A_ITMY = A_BS * 0.0284 = 1.71e-12/f^2 [m/cnt] (@1Hz)


==ITMY to ETMY== (pic.4)
under FPMI lock (TRANSITION_TO_REFL17)
C_DARM * A_ITMY / (1+G_DARM) = DARM1_IN1 / ITMY_ISCINF_L_EXC ...(4)
C_DARM * A_ETMY / (1+G_DARM) = DARM1_IN1 / ETMY_ISCINF_L_EXC ...(5)
A_ETMY / A_ITMY = (5) / (4) ~ 3.54
A_ETMY = A_ITMY * 3.54 = 6.05e-12/f^2 [m/cnt] (@1Hz)


==DARM optical gain==
C_DARM*A_ETMY = DARM1_IN1 / ETMY_ISCINF_IN2 ... (6) (pic.5)
C_DARM = (6) / A_ETMY (pic.6)
Fitting by C(f) = (optical gain) / (1+i*f/(cavity pole)).
DARM optical gain: 6.64e+11 (+/- 3.40e+10) [cnt/m]
cavity pole: 22.2 (+/- 2.02) [Hz]


Please note that each values here are very roughly estimated by using the simplest models.
I have to prepare more accurate models, and will do more careful analysis.
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