Laurence, Lionel · London, School of Optics · leaf 237
Fig. 234. Each zone of a lens has its own focal length, varying from the principalfocus F, for rays refracted in the zones immediately surrounding the prin-cipal axis, to a point where rays A and B passing through the most externalzones, meet the axis. The inability to unite in a single point all… … Fig. 235. the periphery, for that is a natural property of a lens, but to the fact thatthe deviating power increases too rapidly towards the periphery, with theresult that wave fronts are not truly spherical after refraction. In Fig. 235 the opposite points D and E of the lens constitute a portion…
Optics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
