I've taken some pictures and tried to label the beam paths. They're not great, but hopefully they're understandable.
Green is the unsplit laser beam, Red is the CCW beam, Blue is CW (on the AOM side) beam, and Purple is both beams together.
The first three show the incoming and reflected beams. Arrows indicate a reflected beam. The last picture shows the beams in transmission onto the PD.
*Edited to correct first picture |