Thanks. If you can overplot (calibrate it) this on the noise budget on the link in 23945, it would be very more helpful. ok, it is already kinda overplotted, thanks! It seems most of the structures that are not coherent with beam jitter or CARM ones (see 23903) could be explained. Anyway, if they are actually there, considering the coupling path, the meaning is headich to me. As detailed around 22942, we know already some weak points in terms of scattered light in the OMC chamber.
In our past study, shaking between 60-200Hz, there was a large amount of up-converted noise in the DARM.
https://klog.icrr.u-tokyo.ac.jp/osl/uploads/13881_20200329055034_35.png
So I suspect we can't use TF and coherence to evaluate this.
We can reduce environmental disturbances by turning off the FFUs, vacuum pumps, air coolers, etc.
The following are the vibration sources around OMC
If the scattered light is one of the noise sources, the noise in the sensitivity curve using obtained by only one of two PDs for the DC readout can be different because I think it is rare that the scattered light affects completely in the same manner on each PD. If there is no difference in the noise performance of the sensitivity, the possibility of scattered light can be small at the present noise level.
Good point... but if the scattered light might not matter, and the OMC suspension matters, we may actually need to modify it from now...