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VIS (SR3)
fabian.arellano - 15:37 Monday 05 August 2019 (9807) Print this report
Residual motion noise hunting.

This entry reports the search of the main contributions to the optic residual motion. See previous entries 9702 and 9755.

I measured the coherence between the DoF of the optic, IM and IP in ALIGNED and FLOAT states.

  • Directory: /kagra/Dropbox/Subsystems/VIS/TypeBData/SR3/Noise/Measurements/20190805/
  • File: SR3_ALIGNED_TM_OPLEV_ASD.xml, SR3_ALIGNED_TM_OPLEV_ASD_YAW.xml.

The highlights in the ALIGNED state are

  • The seismic environment seems noisier today. See klog entry 9702 for reference. See first picture. The integrated RMS values are

    • TM longitudinal: 0.55 µm,

    • TM longitudinal speed: 0.62 µm/s,

    • TM pitch: 0.21 µrad.

    • TM yaw: 0.28 µrad.

    • Additionally there is a large peak in TM-L, TM-P and TM-Y at 0.158 Hz.

  • There is high coherence between the following degrees of freedom and frequency bands:
    • TM-L and TM-P, 0.150 Hz and 0.9 Hz. This is the reason I suspect of IM-L to TM-P coupling. See the second picture.

    • IM-L and TM-L and IM-L and TM-P, 0.35 Hz to 0.8 Hz. See third picture.

    • IM-P and TM-P, 0.15 Hz and 1 Hz. See third picture.

    • IM-P and TM-L, 0.15 Hz and 0.8 Hz. See third picture.

    • IP-L and each of IM-P, TM-L and TM-P, 0.135 Hz and 0.4 HZ. See fourth picture.

    • IP-L and each of IM-L, IM-P, TM-L and TM-P, above 0.4 Hz has many peaks of coherence up to above 1 Hz. See fourth picture.

    • IM-Y and TM-Y, 1 Hz and 2.3 Hz. See fifth picture.

  • The conclusions of these measurements are:
    • The motion of the IP-L induces motion in TM-P and TM-L in the frequency band from 0.135 Hz to 0.4 Hz. This should be fixed at the IP.
    • The motion of the IM-L induces motion in TM-P nd TM-L in the frequency band from 0.3 Hz to 0.8 Hz. Likely, this should be fixed with IML2TMP and IML2TML control filters.
    • The motion of the IM-P induces motion in TM-P and TM-L in the frequency band from 0.135 Hz to 1 Hz. The motion in the band from 0.135 to 0.4 Hz is likely ground motion coming from the IP, however, the motion from 0.4 Hz to 1 Hz should be fixed with IMP2TML and IMP2TMP control filters.
    • The motion in IM-Y induces motion TM-Y between 1 Hz and 2.3 Hz. This should be fixed with IMY2TMY control filters.
    • The IP does not use currently use inertial damping.
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