The figure below shows the time series of the Y arm + PRMI trail.
(Top plot )
Normalized TRY (intracavity power). It is normalized such that it shows 1 when the arm is locked with the recycling mirrors misaligned.
ASDC and REFLDC in arbitrary unit.
The amount of the arm length detuning observed at the fine frequency discriminator.
At t = 20 sec, the amount of detuning was adjusted so that the cavity power goes to the maximum. At this point the PRM was misaligned.
At t = 30 sec, the cavity length started being slowly detuned to 10 nm. As it is being detuned the intracavity power goes down to almost zero.
At t = 45 sec, the alignment of PRM was restored. Because of that, the REFLDC and ASDC diodes started receiving a large amount of light.
At t = 85 sec, the PRCL and MICH were locked. The REFLDC signal became a high value as the carrier light is mostly reflected. The ASDC goes to a low value as the MICH is kept in the dark condition.
At t = 100 sec, the length started being slowly back to the resonance while the PRMI lock was maintained.
At t = 150 sec, the lock of the PRCL and MICH were destroyed. With the arm fully resonance, I wasn't able to recover the PRMI lock with the same demod signals.
I tried the Yarm + PRMI configuration again.
The PRMI part was locked, but it didn't stay locked during the Y arm was brought to the resonance point.
I will post the time series data later.