The ALS DARM has been locked stably with current suspensions, and the residual DARM motion has been reduced down to ~2 Hz in RMS. This is almost same level with the PRFPMI CARM linewidth. This would help RSE lock a lot.
- UGF is now 20 Hz. This is much higher than privious ALS DARM loop UGF (<10Hz).
- The crossover frequency between MN loop and TM loop is 0.5 Hz.
- I tried to use the IM stage, but it was difficult due to the RM chain resonance at 2.1 Hz. Actually, RM chain resonance is our pain of the neck. I suffered from that resonance also for angular control. We need to damp it somehow...