[David, Rodica, Luke, Giacomo]

After the HAM3 ISI was unlocked this morning, we verified that the table moved small enough that the MC was still flashing.

We then verified the alignment through the HAUX and FI up to IM4, that was still good.

We prepared two iririses at the the nominal height of the beam on the table, placed them before and after IM4 and aligned them to the IR beam to serve as references for the visible laser we will be using for alignment of the auxiliary optics. However, we then realized that IM4 only "nominally" aligned in both pitch and yaw, so this will need to be tweaked tomorrow.

After that, we aligned the REFL beam to the input beam using the PRM surrogate, and the backward rejected beam to the HAM1/2 viewport; we then measured the input beam power (505 uW), and tried to measure the power in the backward beam reflected off of MC3, but we could not distinguish it from the background. Based on the uncertainty on the background measurement (25 nW) we estimated an isolation ratio > 40 db.

Finally, we measured the power in various location of the forward beam (in uW +- 1 uW):

after MC3 = 524

after IM1 = 504

after IM2 = 505

after IM3 = 494

after IM4 = 494

after PRM sur = 15

This yield a 96.2% transmission through IM1 (but we have the wrong polarization), a 97.8% combined "transmission through FI and reflection off of IM3" (although reflection through IM3 should be basically 100%, as it is in the right polarization) and a 3% (as expected) transmission thorugh the PRM surrogate.

Based on these numbers, the REFL beam at at the HAM1/2 septum viewport should be 469 +- 5 uW.  We measured 466 uW: apparently we didn't loose any beam on the way... :-)