Since the frequency of the laser going into RefCav is determined by PMC ,I decided to temporarily remove the PMC for now, so I can scan the laser frequency while aligning RefCav.

It might not be a good idea since the PMC might alter the beam path a little bit, but I just want to align the cavity first.

The plan is after  RefCav is aligned, I'll bring back the PMC and fine tune the beam going to RefCav again.

I still got many higher order modes coming out of the cavity.