[Alastair, Zach]

The bases for our PDs arrived today, which enabled us to finalize the table layout for the new gyro. Alastair has been mounting the cavity mirrors to the new bases and cleaning them for placement into the vacuum system. Here is a shot of the table with rays traced. The (sturdy!) brass PD bases are clearly visible. Note that the MMT lenses shown here are just placeholders; I still need to work out a solution now that the layout is done.

The fact that the "viewports" on the IO box are very close to the edge of it (from when they were used to inject to the gyro cavity) makes the injection setup a little awkward. We originally thought we would have to cross the beams just before the cavity, but I figured out a way to do it without that. Here is a closeup of the injection/REFL isolation setup, and a slightly-less-close-up shot of it to highlight how the beams are directed into the vacuum system. I have only shown the input beams (blue and yellow) in the second one to avoid confusion.

The PD boxes are scheduled to arrive on Monday afternoon. Before they do, I will have two RFPDs ready to go so that we can assemble them and begin open-tank locking immediately. I think we should be able to have an in-vac gyro spectrum by the end of next week if all goes smoothly. Science at work.