Beam splitters for Augmented Reality microscopy, epi-fluorescence, etc

The latest video in the open source PUMA microscope project is out: Beam Splitters and the Advanced Filter Block (plus Microscope Length and Distance RMS/DIN Standards) - YouTube
The project is not just for people building / using the PUMA system but also contains general tutorial information for anyone interested in learning about the optics / mechanics and use of light microscopy (but what better way to re-enforce such learning than to build an advanced microscope yourself from the ground up? This is the PUMA philosophy.)