M. Todd, S. Dwyer

Sheila had the idea to use the measurements that Leo and Camilla took of the SQZ beam and OMC scans to constrain the values of some of the output optics (OM1 and OM2 especially), as they are under scrutiny in our work as well. 

Leo, Camilla, and Jennie performed OMC scans with the SQZ seed beam to estimate the mode matching of the SQZ beam to the OMC. The mismatch they estimated was between 2.2 and 2.9%. See alogs 86445, 85775.

Using the finesse model, we can propagate the q-parameter that was estimated from beam profiles (see alog 85917) to the OMC and check its mismatch with the OMC eigenmode. The path is summarized: ZM5->ZM6->OFI->SRM->OFI->OM1->OM2->OM3->OMC_IC.

The model estimates that this q-parameter measurement propagated from ZM5 to the OMC input coupler has a 2.3% mismatch with the OMC eigenmode. This gives us a lot more confidence in the radius of curvature of OM2, which was previously one of the optics we believed to have a different RoC compared to the reported value. Especially given that if we use the value of OM2 that would remedy the discrepencies in other measurements vs. models (see alog 87872), this would make the modeled mismatch of the SQZ beam to the OMC around 8.6%, which is far from measurements.