I once wanted to make something similar, for sound. I wanted to create active noise cancelling "in the room", instead of via headphones. I pictured these devices combining a microphone and a speaker that you could set up in strategic location. After thinking about it for a bit, I realized that inference would cause areas with silence and others where the sound volume would be doubled. Less than ideal but still possibly interesting. But then I thought about it some more and realized that I needed to think in 3D, which makes the setup orders of magnitude more complex.
It seems like that would apply here as well, at least when looking at the effects of refraction?
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