TJ, Trent, Matt, Georgia, Craig

This morning we went to ISCT1 with the goal of touching up the ALS DIFF beat note (currently sitting at around -13dBm), and investigating the clipping on the ALS Y transmission path, since there visible clipping on the ALSY camera and low-ish transmitted power on ALS-C_TRY.

• Craig took ISC_LOCK to GREEN_ARMS_MANUAL and locked the Y arm
• The rest of us went to ISCT1 with a CDS laptop and monitored the beatnote and the Y arm transmission
• We tried aligning the steering mirror directly before the ALS_DIFF PD in case the beams were clipping, this did not increase the beat note
• We noted that the beams on the DIFF PD were not well overlapped (first photo) and wanted to touch up the alignment of the beamsplitter which splits the beam into the Y arm transmission and DIFF paths
• The Y arm came unlocked, either due to wind of sensor correction being turned off. The Y arm did not reacquire, so we took some photos on the table and headed out

Second and third attached photos show locations where we might be clipping.

Fourth and fifth attached photos show overviews of the ALS Y and Diff paths.

Sixth photo shows what the beam splitting prism looks like at the moment.