Related alogs: 25932 and its comment

Yesterday, we started the preloading test. The CO2 lasers now have an additional common power of about 250 mW, corresponding to an additional common substrate lensing of roughly 31 uD.

• CO2 X 230 mW --> 500 mW
• CO2 Y 0 mW --> 230 mW

Two major conclusions so far:

• ASC loops still functional with the common heating in full lock with 2 W PSL.
• DARM cavity pole seems to be much lower and it is now about 300 Hz.
  • See the attached for the measurement with Pcal X
  • This indicates a worse mode matching between the arm cavities and signal recycling cavity.

We need to decide what optimization we need to for this common lensiong. For testing purpose, we will keep running with this pre-loaded configuration for lock acquisition and for full lock with 2 W PSL.