See pictures in the album BS Remedying work after O3.
We released the IP, F0 and set the three keystones to nominal positions.
- The current position of the F0 keystone and temperature are -1800 um and T = 23.6 °C respectively (O3GK T = 23 °C).
- According to klog 16856, we adjusted the ballast mass to have the F0 keystone at 1250 um when the temperature was 22.9 °C. Now that that the temperature is high the keystone moved down a lot.
- The lifted the F0 keystone with the fishing rod but it reached its upper limit triggering the limit switch. We had to use coil magnet actuation to set it in zero.
- We set the BF and F1 to zero with coil-magnet actuation.
- The RM does not have scratch markings as the SR RMs.
- At the HR side of the optic, the RM has vented screws at the same height as the centre of the optic and we can use them as reference.
- At the AR side of the optic the screws are not at the same height as the centre of the optic, so we cannot use them as reference.
- With the exception of one marking, the reference height markings made by Terada-san and Tomaru-san on the outer frame and pilars are suitable for inspecting the RM from the AR side, where the screws are not at the samer height as the centre of the optic. We used that one marking to check the height of the optic.
- We were unable to use rulers becuase the centre of the optic is too high and we don't have long rulers right now.
- We aligned the laser level and took pictures of it on the RM.
- The diameter of the vent hole in the screw is 2 mmm and we can use it as a length reference to estimate the height from the picture.
- At the right side screw (HR,-X,-Y) the RM is lower than the reference by 3 mm approximately.
- At the left side screw (HR,+X,+Y) the RM is lower than the reference by slightly more then 3 mm.
When the GAS filter keystones are at zero, the BS optic is approximatelly 3 mm below the nominal position.