KAGRA Logbook

Reports 1-1 of 1

VIS (SR3)

fabian.arellano - 14:38 Friday 17 August 2018 (5831)

DC coupling between F0 vertical displacement and the optic yaw as measured by the oplev.

Participants: Enzo, Terrence, Panwei, Hatoya, Fabian.

On Wednesday (15/08/2018) we found a DC coupling between the vertical displacement of the top filter keystone (F0) and the yaw of the optic measured by the optical lever. The reason for this effect is not clear yet and we're in the process of investigating it. As shown in the plot, for a vertical displacement of 250 um of the F0 keystone the yaw displacement of the optic is 215 urad. This is an approximate estimate as the oplev readout reaches its nonlinear region.

Images attached to this report

Comments to this report:

yoshinori.fujii - 21:16 Friday 17 August 2018 (5835)

Thaks for the log, I have two questions just for check, could someone responds to me?:
- I think, on Wednesday 15th, you team opened the top chamber and then add some amount of masses (about 300g like that? please correct me.) on the top-GAS keystone so that the keystone hight came to its nominal position (for a preparation of MD hight tuning). Then, you found that the beam spot on the tilt-OpLev-QPD went away outside the range, which was installed on the other day, klog5673. Then, how did you align the OpLev system? How did you find the beam spot on the center of the QPD again?

- by the way on the MEDM screen, the tilt-oplev signals seem to show up at the windows for length-oplev signals. Can you revise this soon? or do you want to use this configuration for the time being?