Matt, Lisa, Evan

We wanted to remeasure the modematching of the DARM mode into the OMC. At 2 W, the mode mismatch is 2% to 2.5%.

To do this, we used the eLIGO technique of looking at the DARM signal in the OMC reflection QPDs, with the OMC locked and unlocked. Whatever DARM residual is still present in reflection of the locked OMC indicates the amount of mode mismatch.

The attachment shows some of the test mass violin mode first harmonics, as seen in reflection of the OMC. Only about 2% to 2.5% of the DARM signal remains after the OMC is locked.

We need to get data at 20+ W in order to infer the mode mismatch during low-noise operation.

The OMC was unlocked from 07:16:00 to 07:21:00, and it was locked from 07:24:30 to 07:29:30 (all times 2016-03-03 Z).