Laurence, Lionel · London, School of Optics · leaf 241
ther that, within a given time, the rays reach different points of the axis.In the case of a lens the influence of the two surfaces has to be con-sidered, since each ray travels in three different media. If dx be its coursein the first medium/^, d2 its course in the second medium/^, and dz its… … Fig. 242. Influence of Thickness.—A ray A B traversing a thick lens (Fig. 239) isretarded in the denser medium, and can only reach, in a given time, a pointG on the principal axis which lies nearer to the lens than H, the point reachedby a similar ray passing through a thin lens. Thus, spherical…
Optics
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