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Center of Curvature; Principal Axis

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-466

2025-12-18

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Optical Center. - The centers of the spheres whose surfaces bound a lens are its centers of curvature, as C and C′(Fig.1). The straight line passing through these centers is the principal axis of the lens. In plano lenses the principal axis is a line passing through the center of curvature of the curved surface, and normal to the plane surface. The optical center of a lens is that point through which a ray of light passes with practically no change in its direction. In a double convex lens having the same curvature for both sides, it is the center of the figure. In plano lenses it is at the intersection of the curved surface and the principal axis.

Any ray which passes through the optical center, but does not pass through the center of curvature, is a secondary axis, as HO in Fig. 1.