[Jennie, Jason, Masayuki]

Summary:

We aligned the HAM1 output beam to the IMC and verified the power transmission through HAM2. The beam path through JAC_L2/L3 was centered, and alignment to the IMC was improved. Preparation for EOM installation is nearly complete, with final measurements planned for tomorrow.

Details:

• IMC Alignment and Transmission Recovery:

  We initially aligned the HAM1 output beam to the IMC. The IMC transmission signal (TRANS_NSUM) peaked at ~8 counts (with 30 dB whitening) under optimal alignment. However, after Jennie and Jason reverted the MC suspensions, the transmission dropped to <4 counts. We re-aligned JM2 and JAC_M3, successfully recovering the signal to ~6 counts. The second-largest peak was the TEM01 mode, approximately 1/6 the height of TEM00, which we considered acceptable for now.

• Power Check on IOT2 Table:

  With the recovered alignment, we measured 51 mW of power between the periscope mirrors on the IOT2 table. The HAM1 output was measured at 52 mW, confirming that no significant power loss occurred through HAM2. We then centered the output irises accordingly.

• Beam Centering at JAC_L2/L3 and Final IMC Alignment:

  The beam at JAC_L2/L3 was offset by about a quarter inch. We transversely shifted the lenses to center the beam, followed by re-alignment of JM2 and JAC_M3 to re-optimize the IMC transmission. Although JM2 adjustments typically disturb beam alignment through the lenses, only a single iteration was needed to restore IMC alignment. The peak height was slightly better than before this work.

• Irises for EOM Installation:

  Irises were installed between JM2 and JM3 in preparation for the EOM. With this, we believe most of the pre-installation alignment work has been completed.

• Next Steps (Planned for Tomorrow):

  • Measure polarization purity via IMC transmission.

  • Measure the beam size on the IOT2 table.

  • Perform finer alignment of the JAC input.

  • Measure JAC throughput prior to EOM installation.