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  2. Radius of curvature (optics) - Wikipedia

    en.wikipedia.org/wiki/Radius_of_curvature_(optics)

    Radius of curvature sign convention for optical design. Radius of curvature (ROC) has specific meaning and sign convention in optical design.A spherical lens or mirror surface has a center of curvature located either along or decentered from the system local optical axis.

  3. Lens - Wikipedia

    en.wikipedia.org/wiki/Lens

    A burning apparatus consisting of two biconvex lens. A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis.

  4. Thin lens - Wikipedia

    en.wikipedia.org/wiki/Thin_lens

    A lens may be considered a thin lens if its thickness is much less than the radii of curvature of its surfaces (d ≪ | R 1 | and d ≪ | R 2 |).. In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces.

  5. Cardinal point (optics) - Wikipedia

    en.wikipedia.org/wiki/Cardinal_point_(optics)

    The optical center of a spherical lens is a point such that if a ray passes through it, the ray's path after leaving the lens will be parallel to its path before it entered. In the figure at right, [ 8 ] the points A and B are where parallel lines of radii of curvature R 1 and R 2 meet the lens surfaces.

  6. Sign convention - Wikipedia

    en.wikipedia.org/wiki/Sign_convention

    The sign of the weight of a tensor density, such as the weight of the determinant of the covariant metric tensor. The active and passive sign convention of current, voltage and power in electrical engineering. A sign convention used for curved mirrors assigns a positive focal length to concave mirrors and a negative focal length to convex mirrors.

  7. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    by convention, an axis of 90° is vertical, 0° or 180° are horizontal; if the cylinder power is positive, the lens is most convergent 90° from the axis; if the cylinder power is negative, the lens is most divergent 90° from the axis; if the cylinder power is zero, the lens is spherical and has the same power in every meridian

  8. Optics - Wikipedia

    en.wikipedia.org/wiki/Optics

    In the sign convention used here, the object and image distances are positive if the object and image are on opposite sides of the lens. [ 45 ] Incoming parallel rays are focused by a converging lens onto a spot one focal length from the lens, on the far side of the lens.

  9. Vertex distance - Wikipedia

    en.wikipedia.org/wiki/Vertex_distance

    Vertex distance is the distance between the back surface of a corrective lens, i.e. glasses (spectacles) or contact lenses, and the front of the cornea. Increasing or decreasing the vertex distance changes the optical properties of the system, by moving the focal point forward or backward, effectively changing the power of the lens relative to ...