We want to make sure the responses of the PZT actuator does not change after the EP30-2 gluing.
A shadow sensor set up was quickly set-up at the fiber output. It turned out the ring PZTs are something really not-so-straightforward.
If the PZT was free or just was loosely attached on a plane by double-sided tape, the actuation response was quite low (30% of the spec).
After some struggle, I reached the conclusion that the PZT deformation is not pure longitudinal but some 3-dimensional, and you need to
use a "sandwitch" with two flat surfaces with some pressue.
I turned the setup for horizontal scans to the vertical one, and put the PZT between quarter-inch spacers.
Then two more spacers are placed on the stack so that the weight applies the vertical pressure on the PZT.
This is also use ful to adjust the height of the shadow.
The calibration plot is attached. It gives us ~21k V/m.
Voltage swing of 150V results the output voltage change of ~50mV. This is pretty close to what is expected from the spec (16nm/V).
The PZT#3 (which had the mirror glued on) showed significantly large response.
Test PZT #1: 17.4nm/V
Test PZT #2: 17.2nm/V
Test PZT #3: 30.6nm/V
UHV PZT #24: 17.6nm/V
These numbers will be checked after the heat cure of EP30-2