Step by step description of transition from 2arm ALS to Common/Differential LSC for FPMI
- Step 0: Place the frequencies of the arm green beams at the opposite side of the carrier green.
- Step 1: Activate stablization loops for ALSX and ALSY simultaneously.
(Use LSC filter modules for the control. This still requires correct handling of the servo and filter module triggers)
- Step 2: Activate stablization loops for ALS Common and Differential by actuating ETMX and ETMY
- Step 2 (advanced): Activate stabilization loops for ALS Common by actuating MC2 and ALS Differential by ETMX and ETMY
- Step 3: Transition from ALS Common to 1/SQRT(TRX)+1/SQRT(TRY). Make sure that the calibration of TRX and TRY are matched.
The current understanding is that the offset for 1/SQRT(TRX)+1/SQRT(TRY) can't be provided at the servo filter. Figure out
what is the correct way to give the offsets to the TR signals.
- Step 4: Lock Michelson with AS55Q and then POP55Q (PD not available yet) or any other PD, while the arms are kept off-resonant using ALS.
- Step 5: Reduce the TR offsets. Transition to RF CARM signals obtained from POP55I or REFL11I in the digital land.
- Step 5 (advanced): Same as test6 but involve the analog common mode servo too.
- Step 6: Transition from ALS Differential to AS55Q
Independent test: One arm ALS (To be done everyday)
- ALS resonance scan
- Measurement of out-of-loop displacement (or frequency) stability
- Check openloop transer function
Independent test: Common Mode servo for one arm
- Reproduce Decmber CM servo result of transition from one arm ALS to CM servo
Insert 1/sqrt(TRY) servo in between?
- How can we realize smooth transition from ALS to POY11? |