Ophthalmic lenses, dioptric formulae for combined cylindrical lenses : the prism-dioptry, and other optical papers (1900)
Prentice, Charles Frederick, b. 1854 · Philadelphia : Keystone · leaf 169
so great a decentration, must be at least 64 millimeters in di-ameter, and should be ground to a knife-edge to insure maximum thinness.As this example came to the authors notice, the instructions given to the • See page 117. 160 CEMENTED BI-FOCAL LEN6ES SOLVED BY THB PRISM-WOPTRY. mechanic, who… … Fig. 5. Fig. 6. ing its optical center, lay off four points, p. p. p. p., 25 millimeters fromthe center, as shown in diagram Fig. 5 : * Replace the lens on the convex grinding tool, and cut the lens throughthe indicated dotted right-angled diameters into four equal parts. Thiswill secure four…
Lenses
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