Raffaele suggested to put time series together with spectrum of BAB PDH signal. The spectrum was measured in elog2573.

The last time of FC aligned was about one month ago. However, the alignment work took less than 20min today. In addition, the BAB alignment to FC didn't drift away too much. Although I didn't check higher order modes, the BAB transmission was about 430 counts.

After optimizing BAB transmission to about 460 counts, I took time series and put together with spectrum as attached figure.