The Incredible Invasion

The Incredible Invasion also known as Alien Terror is a 1971 film directed by Jack Hill. It stars Boris Karloff and Enrique Guzmn.

Gudenberg, 1890 Professor John Mayer has invented a ray gun which runs on nuclear power. During testing, a ray is shot into space and passes a flying saucer. The aliens decide to come to Earth to destroy the weapon...

Source: Wikipedia