This morning, as anticipated in the entry 69688, we started with a new HWS-INJ measurement to check the WI CH position after the movements performed yesterday evening using the hot mirror on the WI CO2 bench.
Francesco set the ITF in WI single bounce with PR aligned.
The HWS-INJ illumination is shown in Fig.1
07.34 UTC: START HWS ACQUISITION (20260903T0934)
07.38 UTC: WI CH ON (WAVEFRONT 7)
07.48 UTC: WI CH OFF (WAVEFRONT 25)
This measurement confirmed that the CO2 actuators were reasonably well aligned with the RH.
At this point, we went to the Laser Lab with Suzanne and Piernicola to try to improve the centering of the HWS-INJ beam on the WI mirror.
As a first attempt, we performed a pure shift using EIB_HAR_M0 (see Fig. 3). The vertical alignment was easily corrected by a small counterclockwise rotation of the mirror (see Fig. 4).
The horizontal alignment was more challenging. We tried moving the horizontal knob in both directions, but we were not able to obtain the required displacement.
We then tried to recover the alignment using the usual procedure, by superimposing the HWS beam on the green beam. Although we were able to achieve a good overlap, the beam was still clipped on the CCD and no further horizontal adjustment was possible, as the corresponding knob had reached the end of its travel range.
At this point, we rotated the mirror around its axis to move the adjustment away from the end of the travel range. We then realigned the HWS beam with the green beam and also checked the beam reflected back from the WE. The returning beam is shown in Fig. 4.
At this stage, the alignment appeared to be recovered. However, a new HWS acquisition with the WI RH showed that the RH signature was still approximately in the same position as at the beginning (see Fig. 5).
Tomorrow morning we will try to optimize the HWS beam alignment around this position.
To be noted: in order to ease the alignment of the HWS beam on the green, we temporarily removed the automatic check of the presence of the CEB GREEN BEAM in ARM_LOCK automation node (lines commented at #311 and #828). To be reverted once this work will be finished.