I am no expert, but I believe that picture is pretty much ready for action. Ours at Solent Sky is the same. I do know that the prism is not glass but is made of Arsenic Trisulfide, which is near transparent to infrared (pretty important when designing a heat seeker nose).
Take a look at this pic elsewhere on PPRUNE...
http://i38.tinypic.com/jfi4i8.jpg
Although many pictures show the dark red plastic ground cover used to protect the prism, when loaded and ready to go, it's as my picture above.
I think the same is true of its successor, the Red Top...see below...(again at Cosford)
but I am no expert, as I said.
We have a Red Top on the other wing of our Sea Vixen (sorry, you cannot have that either
)
Corsairoz
