Rick Savage, Dan Chen, Shingo Hido, Emmanuel Makelele and Dripta.
We went down to EY on Thursday, July 18th, 2024 to do a Pcal measurement, mostly to show the measurement procedure to our visitors. We used the procedure outlined in T1500062-V17 as a guide. A scanned copy of the filled out measurement procedures and log is attached.
Before we began the measurement, a picture of the beam spot position was taken. It shows that the beams were centered on the Rx sensor apreture (BeamSpotBefore photo attached).
As noted in the scanned copy, after the first background measurement while WS was placed in the Tx module, the shutter stopped working. We could not open the shutter locally or remotely. The shutter has now been removed from the EY Tx module for troubleshooting. Pictures attached.
We continued with the measurement manually shuttering and unshuttering the laser. After taking all the measurements, a beam position picture was taken. It shows that the bemas remained centered and the Pcal beam spots did not drift significantly during the measurements (BeamSpotsAfter photo attached).
Analysis and results/plots to follow.
The analysis and report can be found in git: https://git.ligo.org/Calibration/pcal/-/tree/MergingBranch/O4/ES/measurements/LHO_EndY/tD20240718?ref_type=heads
The report LHO_EndY_PD_ReportV3.pdf shows that the latest Rx reponsivity measurement is within 5 hop (hundredths of a percent) of the mean value and the optical efficiency is within 10 hops of the mean optical efficiency value.