Definition of "sunbeam"

I cut-in various other material to this; for instance, a shot of a rushing brook in springtime, with dancing sunbeams reflected in the water; of birds splashing in the village pond; and, finally, of a laughing child.

1957, Rudolf Arnheim, Film as Art, page 90

Similarly, the rays diverging from the sun will pass by you and converge on the point directly opposite the sun, the shadow of your head. All sunbeams, and thus all shadows, appear to converge there. […] Only perspective makes all shadows appear to converge on the antisolar point. But this point is also the center of the rainbow, so as you look at the rainbow, all sunbeams and shadows will lie along radii of the bow as they flow straight to its center.

2001, Raymond L. Lee, Alistair B. Fraser, The Rainbow Bridge: Rainbows in Art, Myth, and Science, page 116

I had frequently had to explain to cameramen that only in the early morning or late in the evening did sunbeams fall from the window as flat as they were usually found in films. The sun being higher during the hours of work, another way of showing sunbeams had to be found.

2008, Lotte H. Eisner, translated by Roger Greaves, The Haunted Screen: Expressionism in the German Cinema and the Influence of Max Reinhardt, published 1952, page 68

DOCTOR: You seem to be our best bet so far, don't you think so, Mel? Mel? Where's Mel?DEPUTY: No, no, no, sunbeam. You're coming with us.

1987, Doctor Who (TV series), Paradise Towers (aired 5 October)