Ophthalmic lenses, dioptric formulae for combined cylindrical lenses : the prism-dioptry, and other optical papers (1900)
Prentice, Charles Frederick, b. 1854 · Philadelphia : Keystone · leaf 44
Fig. 29.Concave Sphero-cylindrical Lens (— s* O 4- c^ axis 180°) — Periscopic Form. In the above figures, i, e, and/ are associated with horizontal, and <*, c, andy* with vertical refraction. COMPOUND LENSES. 3, CONTRA-GENERIC MERIDIANS (CONVEX AND CONCAVE). § 37. Hitherto we have considered… … Fig. 30.Concavo-convex Cylindro-cylindrical Lens (— c axis 90 O + c* axis 180°). sections. In contradistinction thereto, and as a final complication, wemay combine in a lens different or even like degrees of refraction, thoughof opposite type; namely, convex in one and concave in the other…
Lenses
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