I tuned fiber cancelation loop after fiber alignment.

 

The X side seems good.

The Y side FIB loop seemed closed (Because the Guardian state indicated “locked”.),  but actually it oscillated.

So, I changed the input gain of FIBY servo from -19db to -16db.

Currently, It's seems good.

 

Note:

The fringe of Y side cancellation interferometer is about 3 times smaller than X side counterpart (fig).

It might have to fix cancellation interferometer alignment by adjust reference path mirror or something.