R&D (FilterCavity)
YuhangZhao - 14:42, Monday 17 May 2021 (2505)
Rough estimation of filter cavity AA and pointing loop bandwidth

I used strip tool to check how long time AA/pointing loop needs to use to go from unlocked point to locked point. This tells us rouhgly the bandwidth information of these loops.

The AA loop filter and gain are as following:

  Input pitch Input yaw End pitch End yaw
filter DCdamp2 DCdamp2 DCdamp2 DCdamp2
gain -0.002 -0.005 -0.002 -0.005

Note that these filters and gain are not optimized yet. The time to go from unlock to lock is shown in the attached figure 1. We can see it took about 5 second, which means the bandwidth is about 200mHz.

The beam pointing loop filter and gain are as following:

  BS Pitch BS Yaw
filter int int
gain 70 15

Note the pointing loop gain is not optimized yet. The time to go to the good point is shown in the attached figure 2. We can see it took about 2 min, which means the bandwidth is about 8mHz.

Images attached to this report
2505_20210517074317_aabw.png 2505_20210517074322_pointingbw.png