Changing Visible Light into IR and then back

[T.O.E Dream]

Is there a way to change visible light like the light coming out of the screen you're reading into infrared or any other invisible light and then take that and change it back somewhere else? What I'm what i'm trying to do is make a computer screen or maybe a T.V screen visible to only those who are wearing a certain type of goggles, that changes IR light back into visible light. Is this possible? And if so is it easy?

 

[Andy Resnick]

Sure- with active optical elements. The downconversion (lower energy) can be done passively (and trivially) if you had a suitable fluorophore or phosphor. However, the upconversion requires energy.

So no- not easy. Even harder for an imaging system.