I put the ETMY trans QPD in.
The ETMY trans beam was already going toward the TRY DC PD, and a CCD camera. I put a beam splitter in that beam (reducing the power to TRY and the CCD by 50%), and sent my picked-off beam to the ETMY QPD. Since there is a lens in this path to focus the beam onto TRY and the camera, I put the QPD ~the same distance from the lens as the camera. Due to space requirements (because of all the green stuff on the table now), I had to put a Y1 turning mirror between the beam splitter and the QPD. The beam is aligned onto the PD, although the signal isn't super strong. When the PD is blocked, the sum is ~(-92 counts). When the beam is on the PD, the sum is ~(-78 counts).