NaokiAritomi - 23:05, Thursday 03 September 2020 (2200)
CC1 saturation is caused by filter cavity
We have a problem of CC1 saturation and we found that the CC1 saturation is caused by FC lock/unlock. We should lock FC first and then lock CC1.
Comments related to this report
YuhangZhao - 01:04, Friday 04 September 2020 (2201)
Just to add a bit more information about my understanding. If CC1 loop is locked first, the lock of filter cavity causes the light from main laser having a large phase change. Then CC1 loop needs to give a large correction to keep the same phase. In the end, it causes the saturation of CC1 correction signal.
Matteo also suggested to feedback correction signal to the end mirror, which will offload the large correction sent to main laser.
Just to add a bit more information about my understanding. If CC1 loop is locked first, the lock of filter cavity causes the light from main laser having a large phase change. Then CC1 loop needs to give a large correction to keep the same phase. In the end, it causes the saturation of CC1 correction signal.
Matteo also suggested to feedback correction signal to the end mirror, which will offload the large correction sent to main laser.