It is a well known process, Not a lot of general use so costs are not low, but not nearly as high as the original disney prism, I would guess around a 1000 USD for one. As far as I can tell any well equipped optics laboratory could make a beam splitter with whatever frequency gate they want.

https://accucoatinc.com/technical-notes/beamsplitter-coating...

I have no idea about that specific company I just picked it after a search for "beam splitter"

After I saw that video on the sodium vapor illumination process I was curious as to what if you could instead use near-IR light as the mask illumination. In theory you would have a perfect mask(as in the disney process) and no color interference. I found that frequency gated beam splitters are a fairly common scientific instrument.

Thanks for the info.

As for the IR idea, I wonder if there's something like a crowdfunding/crowdsourcing site for ideas where the person who had the idea doesn't really want to do it, but leaves it open to others to try. You said you "don't really have the budget to try it out", but let's say even if you had the money, it wouldn't be a priority for you, as you're not an expert or you have better things to do or whatever. Is there a place to just shout ideas into and see if any market-oriented entity would take it upon themselves to try doing it? Besides forums full of ideas like "tinder but for X" and such crap? Because, imagine if your idea really is a great one. A couple hours from now it would be buried in HN.