I measured the transmission of the Coastline 1m mirror at 180. ppm (S122C).

Alignment procedure while setting location of optics:

1. use 2x irises to constrain a beam path at the locations of the eventual MZ input BS and the cavity BS.
2. Place the first (R~1) flat mirror at 45 degrees centered on the beam line. Use this mirror to steer into an iris at the location of the cavity's curved mirror.
3. Use steering optics to direct the eventual transmission beam into the trans mon PD (PDA 20CS)
4. Place the curved mirror at near normal incidence. Use this mirror to steer the beam through irises at the location of the MZ output BS and cavity BS.
5. Use steering mirrors to send the beam to the refl PD (PDA255).
6. Place the cavity BS and steer the reflected beam to the refl PD.

Alignment procedure subsequently:

1. Misalign the cavity BS
2. Use the cavity mirrors to steer the circulated reflection into refl PD.
3. Use cavity BS to align prompt reflection into refl PD.