light gun 
noun
A handheld gunlike photosensitive device used chiefly in computer games, held to the display screen for passing information to the computer.Your television screen is coated with a stuff called phosphor that lights up when the light guns shine on it....
- The new light gun will blow you away with its pixel accuracy and sleek pistol grip.
- When the controllers are connected to the light gun attachment, it works pretty well.