HN Reader

Are safety and environmental factors being consideration here? Putting thin films of some mercury compound into consumer electronics doesn't sound great, and is probably already banned by regulations like RoHS.

This is so far out of my expertise that I have nothing to add to the actual topic, but I must say that the veritable forest of beam mirrors, splitters and whatnots looks fascinating. It reminds me a bit of the early integrated circuit research where people had similar forests of transistors.