Dhruva, Vicky. We improved IR mode-matching into the filter cavity, to use the refl dip to estimate losses now at the edge of FC2, before moving the cavity axis towards the FC2 optic center. FCGS VCO scanning script in /opt/rtcds/userapps/trunk/sqz/h1/scripts/filterCavity.
Dhruva is measuring the position of the beams at which we saw this nicely mode-matched FC-IR cavity scan. We used Naoki's dither-optic-spot DTT template is saved in his home Desktop folder. For this cavity scan, the beam spot, measured using optic dithers, was:
- FC1: pitch -5.5 mm, yaw -3.7 mm
- FC2: pitch +2.9 mm, yaw -23.8 mm (checked, this is same as a few days ago, LHO:66132). Νicely mode-matched FC-IR.
We then used FC1 to center the beam on FC2, moving FC1 yaw from -49 to -68. Dither technique measures the beam on FC2 at
- FC2: pitch +7.3 mm, yaw -12.8 mm. AKA, beam has moved 4.4mm in pitch, +11mm in yaw on FC2, and clears the VP with a bit of clipping. Mode-matching here is decent, mostly from mis-alignment.
Analysis of losses from IR refl dips to come. In the meantime, some funny pictures of how we tried to track the FCGS beam spot movement with FC2 camera, hard to say if the spot is getting less lossy as we get towards the optic center, but not impossible?
