What is the word for the portal/lens in Heaven that God(s) watch Earth through?

It has the same sort of function as a witch’s crystal ball, where God(s) in heaven can zoom in on different humans, and watch their life and what they are doing. It has been used in old paintings and several sci-fi movies, but I cannot find much reference or a word for it. It’s been represented as a large glass circle, sometimes cloudy, sometimes with stars. Does anybody know if there is a term for this type of portal / lens used to watch the earth through?