On Friday 16th of August I measured the residual motion of the optic in ALIGNED state. There was a typhoon in the neighborhood.
In ALIGNED state the optic longitudinal RMS displacement and velocity DO NOT fulfill the requirement.
This table shows the integrated RMS displacement for each degree of freedom and the requirement.
| Degree of freedom | ALIGNED | Requirement | klog 9704 |
| Longitudinal displacement | 0.44 µm | 0.4 µm | 0.16 µm |
| Longitudinal velocity | 1.09 µm/s | 0.5 µm/s | 0.21 µm/s |
| Pitch displacement | 0.31 µrad | 1 µrad | 0.047 µrad |
| Yaw displacement | 0.17 µrad | 1 µrad | 0.060 µrad |
Relevant notes:
- There's no Inertial damping.
- There's high coherence of TM-L with the IP motion measured with the LVDTs from 80 mHz up to 630 mHz. See plots attached.
-
The amplitude spectral density shows harmonics of three fundamental peaks. In units of Hz:
- 0.682: 1.353, 2.033, 2.713, 3.377, etc.
- 1.018: 2.033, 3.041, 4.057, 5.072, etc.
- 1.354: 2.713, 4.057, 5.408, etc.
- These peaks have a non-negligible contribution to the integrated RMS values.
Other notes
- Directory: /kagra/Dropbox/Subsystems/VIS/TypeBData/SRM/Noise/Measurements/20190816/
- File for ALIGNED state: SRM_ALIGNED_TM_OPLEV_ASD_190816_1565940969.xml
- Bandwidth of the displacement measurement' from 0.010 Hz to 800 Hz.
- The bandwidth of the optic velocity measurement was from 0.010 Hz to 10 Hz. Above 10 Hz there is a lot of noise which I don't believe is real displacement of the optic. The peaks are likely related to the oplev optics support platform
- Related entries: 9704.
