I finally got round to comparing the visibility measurements we took in this entry and comparing them with the mode scan taken on April 16th before our mysterious drop in optical gain possibly due to the OFI.

April 16th Measurement:

HOM mis-match from scan = 0.09825 = 9.83% calculated using inferred height of carrier 02 and carrier 20 modes and the measured height of the carrier 00 mode.

HOM mis-match from visibility =  9.763 %

round trip loss: 3504 ppm

Measurement taken on April 30th - old alignment 

HOM mis-match from scan = 0.08454 = 8.45% calculated using inferred height of carrier 02 and carrier 20 modes and the measured height of the carrier 00 mode.

HOM mis-match from visibility = 19.870 %

round trip loss = 3289 ppm

Measurement taken on April 30th - new SR2 and SR3 alignment:

HOM mis-match from scan = 0.09954 = 9.95% calculated using inferred height of carrier 02 and carrier 20 modes and the measured height of the carrier 00 mode.

HOM mis-match from visibility = 14.415 %

round trip loss = 3495 ppm

The round trip loss seems to have been worse after the OFI problems started but I can't reconcile the two methods of measuring mode mis-match. In any case it seems like out current alignment has brought our current OMC round trip loss and the mode mis-match (as inferred from mode scans) back to the April 16th values.