Hi Wertpol,
I don’t believe that raytracing will work without the sprites having some kind of collision. I’m not sure of a way to get this to work using sprites as you are attempting but I can offer an alternative. I would suggest looking into 3D widgets and having one imitate a computer screen. You can find a tutorial for beginning with 3D widgets here:
https://docs.unrealengine.com/latest/INT/Engine/UMG/HowTo/Create3DWidgets/index.html
I believe this would be the best way to go about making a computer screen in-game.
Have a nice day