Continuation of 11447.

Attached are several different OLG measurements with the cavity locked. The differences are as follows:

Thorlabspiezo-differentsm1tightness.png is the thorlabs piezo on both traces, without adjusting the controller shape. The active trace is screwing in the SM1 ring a fair amount, almost no slack left.

noliacpiezodifferentsm1tighness.png is the Noliac piezo on both traces. Additionally without changing the loop shape (between the two measurements, but changed from piezo to piezo). The active trace is again screwing in the SM1 ring a good amount.

Differentpiezos.png is a comparison of the two piezos with the same loop shape. Note the large difference in UGF.

Take aways:

1) Tightening the SM1 ring doesn't seem to effect the OLG when using the thorlabs piezo. Therefore I'm not sure its worth testing the stiffnesses of the o-rings used in the set up for the thorlabs piezo. For the noliac, it does seem to flatten some lower frequency parts of the OLG. It also lowered the UGF.

2) The 3.3 kHz mystery feature is in the transfer function of both piezos. If this feature is eliminated, I think the thorlabs piezo could become sufficient for locking these cavities with a mirror.

I think we should buy some more of the thorlabs piezos at different sizes, as they are relatively cheap, and test them on this cavity.