trying to verify our FE model for both cavities. In order to measure the coupling i tried different versions of attaching a "shaker" or PZT  to the table to excite the table in vertical direction. As i'm worried about attaching something to the floating table as it could easily destroy the attached PZT or shaker i try to excite the non-floating table. The best solution i found is to put a PZT right below the vacuum chamber underneath the optical table. It does not look very sturdy but the performance is very good. Driving the PZT with only a few volts using our HV piezo amplifier (old, modified PMC servo) i can easily get an SNR of 100 above the seismic noise. And it's making a lot of noise if you drive it even harder. Turns out that the optical table is a good loudspeaker. Also driving it a low frequencies one can feel the whole lab vibrating!

Measurements of the coupling are currently performed. Check back later...