We performed the settings of oplev wind shield for MN YPL(TILT, LEN).
1. Performed the centering by checking the DC QPD signal
- At this time, we removed the ND filter and fixed the MN LEN QPD.
2. Measure the spectrum as reference (Blue spectrum of Fig.1. and Fig.2.)
3. Set the wind shield to Injection port
- We carefully checked the signal during this work
- After this work, the position of the oplev singal on the TILT QPD moved upper part
- Maybe it became heavier, the also moved the same level on the ROL QPD signal
- We centered the signal by only touching the injection part
4. Same work to receiver part.
I compared the spectrum before and after setting the wind shield.
1-20 Hz decreased may be caused by air disturbance.
We will wait good noise budget result by Chiba-san and Kasamatsu-san.
It might become difficult to set the wind shield before finalize the oplev alignment and calibration,
because access to dial gauge became difficult.
But we will remove this wind shield once because we will perform the black spray coating to avoid the effect of scattered light.
