[Aritomi, Yaochin]

We put TAMA PD in the reflection path from filter cavity and detected CCSB 14MHz beat note and demodulated it with TAMA demodulator. Filter cavity is locked with green and CCSB are off resonance. For demodulation LO, we used CC1 demodulation LO. Then we scanned green phase going to OPO which scans relative phase of CCSB. This relative phase scan of CCSB emulates CCFC error signal.

Note that we only have 90:10 RF BS and when we used this RF BS to divide CC1 LO and used 10% of CC1 LO for this filter cavity error signal, there was no error signal. We'll buy 50:50 RF BS.

Pic.1: CCFC 14MHz signal 

Pic. 2: CCFC 14MHz signal after RF amplification (34dB)

Pic. 3: CCFC error signal for filter cavity when CCSB are off resonant and green phase is scanned