georgia.mansell@LIGO.ORG - posted 16:00, Wednesday 14 November 2018 - last comment - 08:21, Thursday 15 November 2018(45279)
ISC HAM1 work today - POP beam diverter replaced, inital tests of LSC-REFL_B completed
Keita, Richard, Corey, Craig, Georgia
- We have installed the new HR optic and circular black glass dump in the POP beam diverter [ECR 1800329]
- The previous optic, shown in photos 1 and 2, was a 90/10 splitter. The wedge was on the septum-side, which is the side which is not covered by the mount in photo 1.
- The new optic is DCC-E1100048, serial number 2.0-0947.
- The black glass we installed behind the beam dump showed some scratches, watermarks, and foggy patches on both sides. Side 1 is shown in photo 3, side 2 is shown in photo 4. We installed the glass anyway, as there should not be significant power leaking through the HR optic in front of this. I believe we put side 2 facing the beam.
- We did some initial testing of the new LSC-REFL_B photodiode [ECR 1800316]
- Keita hooked up the D-25 cable and RF cable. He noted the connector at the photodiode end was a little loose, shown in photo 5, and tightened it.
- Keita shone a flashlight on both LSC-REFL_A and LSC-REFL_B and we monitored the LF outputs, they showed comparable signal.
- Cable clamps were installed for the two cables to the photodiode.
- We inspected many of the beam dumps on the table. Keita noted that the beam dump for the beam reflected off the REFL_B_WFS had two watermark-like features (photo 6). We plan to replace this beam dump.
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For now,
- REFL B is only held at an approximate place using just one screw.
- 50:50 BS for REFL_A REFL_B splitting is yet to be installed.
- Black glass beam dump for REFL_B is yet to be installed.
- 5-way coax continuity check was done for the feedthrough but we don't know if the RF connection at the diode is good.
These are finalized/installed/checked on Saturday after the PSL beam becomes available and IMC locked in vacuum.
Here is some experience on cleaning the foggy patterns on black glass: https://nodus.ligo.caltech.edu:8081/OMC_Lab/283 https://nodus.ligo.caltech.edu:8081/OMC_Lab/283