There was some talk in today's commissioning meeting about beamsplitters added to the in-vac POP path (if I understood correctly, audio was poor).
I went back to some photos I took during our November 2018 HAM1 incursion (sorry these particular photos didn't make it to that alog). Most of that work was on the REFL path but I did take some pics of the optics in the POP path on the side.
I've attempted to label them based on the HAM1 ISC layout, I've used descriptive rather than official names. I don't see any undocumented optics (unless something was replaced inside an existing mount?).
Keita informed me that the discussion was in fact about additional beam splitters on the REFL path. I found another photo from November 2018 showing the REFL path in HAM1, see attached. There are no additional beam splitters in the REFL path; the mirrors in the path are all accounted for in V14 (file name is V12...) of the HAM1 layout. M14 is a 90/10 splitter with high power beam dump on reflection, M17 is a 50/50 splitter with the reflection going into the same high power beam dump (not a separate black glass beam dump as shown in the layout diagram) and M1 splits REFL into the in-vac and in-air paths.
That part of the REFL path hasn't changed since Sept. 2013, it seems (Kiwamu's alog 7883).