The Blaster Beam is an instrument used to create sound effects and occasionally parts of musical scores in sci-fi, horror & fantasy films, just like better known instruments like the theremin, apprehension engine, and waterphone:
The most obvious example- at least to those who frequent THIS site- is from the first Star Trek motion picture.Those sounds, sound...familiar, but I can't place what films I've heard them in...but I know I've heard them in some movies.