So, MgF2 has a boiling point of 4100 F. That's pretty hot. So you'd need to achieve this temperature and get the gas inside a container with your lens, like cigarette smoke on your windows. Hmm... I need to think this thing through. A bell jar seems easy enough to come up with. A vacuum pump could be the intake side of any air compressor. I saw a fancy machine on ebay for several thousand dollars, but certainly don't have a pile of cash I can peel off a few bills from. Certainly this can be done at home.
As I said, you need a way to vaporise the stuff in vacuo. That means inside the bell jar under vacuum, so it can condense in the surfaces you want to coat. Think of electricity.
So if this process is akin to silvering telescope mirrors, shouldn't I be studying the home-making of telescope mirrors? All I'm saying is certainly this can be done without going into the poorhouse. Thanks.
BTW--I've got my customer shipping me a quart of methylene chloride on the lens separation project. Acetone and boiling were worthless. My buddy want to put it in his pressure-cooker. I'm a bit more conservative and patient.
Sorry OP for hogging your thread. I wonder if this vacuum would have to be as high as the inside of a radio tube.
Lets see... An old Nuarc platemaker uses HV to strike an arc with carbon sticks. This causes smoke. The smoke fogs up the vacuum frame glass. Substituting MgF2 in this analogy, you would want the gas from that to deposit on your lens. From that point the coated lens is to be baked to get the deposit like glazing pottery.
I once read of someone using something like this:
It was better than throwing the lens away.
The trouble is that anything in a vapor phase will deposit on anything cooler than it, so I don't think a carbon arc would produce a clean enough MgFl vapor to result in a useful coating. It would sure supply the heat though.
Look into the work done by Katherine Blodgett for Generous Electric.