TJ, Daniel, Peter F, Sheila, Jenne, Rich, Dan Brown, Georgia, Craig

This morning Peter King and Jason went into the PSL and made some alignment changes to the FSS.  We believe that while this was happening, some misalignment occurred which shifted the frequencies of both end station and the squeezer laser, but not the main laser itself (Attachment One).  Most likely this is due to some misalignment through the FSS AOM catching a single-pass diffracted beam, and not the expected double-pass.

This was first noticed by TJ, who plotted the ALS_COMM beatnote and saw it was low (from +6 dBm to -20 dBm) starting around this morning (Attachment Two).  Sheila and Jenne went out to align the beams on ISCT1, but were unable to recover ALS_COMM beatnote.  They looked at the beatnote on the scope, and found it was at 240 MHz, and not the expected 80 MHz.  ALS_DIFF was still at the expected 160 MHz.  The transmitted and reflected power coming from the FSS both increased.

Daniel and Peter F looked at all the laser frequencies this morning (attachment one), and found all of them shifted by about 100 MHz except the main laser.  I plotted the IMC gain from today and a couple days ago, and found the gain reduced by about half. (attachment three).  This is consistent with losing half of our actuation range from the IMC VCO + AOM.

We hope that tomorrow morning we can have another incursion into the PSL to see if this is actually the case, and try the realignment again.  None of us are going in tonight.