One of the things that was noticed on ISCT1 is that some of our beam combining beam splitters have beams that are hitting the back side of their mounts rather than the beam dumps behind the mount.  In particular, I think Keita said that ALS_BS6 on D1201103 had a problem.  I don't know if Sheila and Georgia noted that also ALS_BS3 on that diagram has a problem currently, or just potentially. 

One way to solve this problem is utilize a mount that gives clear access to all 4 ports of the beam splitter.  It sounds like BS6 currently has a New Focus 9809 mount which should suffice, but we still have some clipping problems there.  BS3 just has a standard mount, so definitely needs something.  I have had success at the 40m ALS beam path using Thorlabs H45s.  I also note that we have 2 New Focus 9925 mounts in the optics lab.  I'm not sure if these are made any more, since I can't find a website for them, but they would work too, and we already have them, so we can swap one into the BS3 mount.  I attach a photo from my phone of this last mount.

(Mostly writing this down so I can remember the part numbers, since I struggled to remember what the 45deg mounts from Thorlabs were called.)