[Peter K, Koji]

Quick report. We went into the PSL table and worked on the EOM replacement. After some recording measurements, the EOM was replaced. This (of course) caused some misalignment of the beam after the EOM. We investiagted how to recover the beam alignment to the IMC, but the beam alignment has not been fully recovered. We saw a spot on the IMC REFL camera and some HOM fringes on the IMC Trans camera.

- Measured the previous modulation depth with an optical spectrum analyzer (OSA).
- Measured the delivered RF power to the each port of the EOM + new cable.
- Measured the previous EOM optical transmissivity.
- Installed an HP RF amp (gain of +16dB) to the new 24.1MHz RF path
- Combined 24.1MHz and 45.5MHz with a power combiner

- Removed the previous EOM from the aluminum mounting block (found two of the four previous screws were not tight at all and two others were not fully fastened!)
- Installed the new EOM on the aluminum mounting block.
- Maximized the EOM transmission with the knobs of the tilt-aligner. We saw good amount of transmission.

- Checked the alignment of the EOM transmission. Found the beam is not going through the first iris after the EOM.
- Touch the HR mirror right before the EOM to have the beam recovers the centering on the first iris -> Saw some beam on the REFL DC and some higher-order mode fringes at the IMC transmission camera.

- We proceeded to make progress on the EOM installation.
- Measured the new modulation depth and adjusted it to have the same modulation depth as before. For the 45MHz modulation, the modulation depth did not reach the previous level with the max power.

I (Koji) will add more quantitative notes later.