light_beam has definitions from the field of physics
[ noun ] (physics) a column of light (as from a beacon)

Used in print

(Francis J. Johnston and John E. Willard, "The...)

The round cells were reproducibly positioned in the light_beam which entered the thermostated mineral_oil bath through a window .

(A. N. Nagaraj and L. M. Black, "Localization of...)

The light_beam from the lamp was filtered through a half standard thickness Corning 1840 filter .