make text visible with shining flashlight over it. Possible?

I got a question maybe you don't know the answer on it. But is it possible to make invisible text visible when you shine a light on it. Like for instance you got a dark/black background without text(text is invisible/hidden). But then when you shine a flashlight over the black background the text becomes visible in the circle form as big as the light itself is. Is this kind animation/effect possible to create? Or something like this that trough light text slowly comes visible where you shine on it....