I planned the layout for new fss setup.

The new setup has 1) both cavities placed in the same vacuum chamber, 2) two AOMs used in both RCAV and ACAV paths, 3) more compact beat path.

 In the layout, I assumed that

• Two cavities in the chamber are 3 inches apart.
• Two AOMs are of the same model, have the same setup
• There is no change of plan for the layout between PMC and the laser

This is just a plan, no mode matching has been calculated yet.

I am concerned  that the mode matching lens might block the beam in ACAV path where the incoming beam and reflected beam cross, but this can be adjust later.

The outer foam box will be smaller, but it should have enough space to keep some electronics inside like we have now.

I should find two similar sets of beam splitters/ mirrors for beams in the beat path behind the cavity. So the pick up beams from two cavities can have same power.

Right now the power going into two PDs for RCTRANSPD are not the same because the splitter are not the similar.

Note that we might install a platform  behind the cavities so that we don't need the periscopes to lower the beam, and get rid of their associated mechanical peaks.