CAL group
We did the calibration measurements and updated the parameters.

Estimated parameters in the Pre-maintenance measurements are as follows.
 H_etmxtm      = 3.249400427e-14 @10Hz  ( -16.86% from previous measurements)
 H_etmxim      = 9.690969231e-15 @10Hz  ( -34.86% from previous measurements)
 Optical_gain  = 3.028677809e+12        ( 60.13% from previous measurements)
 Cavity_pole   = 16.605092068 Hz        ( -9.64% from previous measurements)

Previous values are listed in klog#35612.

Compared with the previous measurement, the absolute values show a significant change. This is primarily attributable to (i) the disengage (klog#36219) of “LSC-OMC_DC [FM5]: 3.123 dB”, (ii) the gain change (klog#36150) of “VIS-ETMX_TM_LOCK_L [FM4]”, and (iii) the cavity-pole shift associated with the recovery of the finesse.

From the ratio of the sensing functions between the previous and current measurements (Fig. 2), I observe an increase at the ~1% level. In contrast, the ratio of the actuator functions indicates an increase of about 10%. Since the high-frequency region of the actuation function is dominated by the TM stage, these results imply that the actuator efficiency of TM stage increases by approximately 10% as the temperature rises. The observed phase difference is explained by the difference in the time-delay term introduced in the fitting.

--- Cross-check calculations ---
(NEW_H_tm * NEW_TM_LOCK_L_FM4) / (OLD_H_tm * OLD_TM_LOCK_L_FM4) = (3.2494*1.3229952) / (3.9082 * 1.0084176) ~ 0.755 dB

abs((NEW_H_c / (1+1j*1000/NEW_cp) * NEW_OMC_DC_FM5) / (OLD_H_c / (1+1j*1000/OLD_cp) * OLD_OMC_DC_FM5)) = abs((3.0286 / (1+1j*1000/16.605) * 1) / (1.8913 / (1+1j*1000/18.3763) * 1.43268)) ~ 0.0865 dB

As a consistency check, I confirmed that the ratios computed by including the corrections due to the gain and filter changes agree with the ratios in Figs. 2 and 3. Note that the gain term of OMC_DC is normalized when computing the optical gain; therefore, it is not explicitly written in the above equation.