The light rays of the parallel light beam that have passed through the convex lens converge at point F. The concave lens disperses the light of the parallel light beam so that the extensions of the scattered rays intersect at point F.
The light rays of the parallel light beam that have passed through the convex lens converge at point F. The concave lens disperses the light of the parallel light beam so that the extensions of the scattered rays intersect at point F.