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  2. Cylindrical lens - Wikipedia

    en.wikipedia.org/wiki/Cylindrical_lens

    Cylindrical lenses. A cylindrical lens is a lens which focuses light into a line instead of a point as a spherical lens would. The curved face or faces of a cylindrical lens are sections of a cylinder, and focus the image passing through it into a line parallel to intersection of the surface of the lens and a plane tangent to it along the cylinder's axis.

  3. Photographic lens design - Wikipedia

    en.wikipedia.org/wiki/Photographic_lens_design

    Prime lens - a photographic lens whose focal length is fixed, as opposed to a zoom lens, or that is the primary lens in a combination lens system. Zoom lenses - variable focal length lenses. Zoom lenses cover a range of focal lengths by utilising movable elements within the barrel of the lens assembly.

  4. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    A prescription of −1.00 +0.25 × 180 describes a lens that has a horizontal power of −1.00 D and a vertical power of −0.75 D. Only ophthalmologists write prescriptions in + cylinder. An optometrist would write a prescription in - (minus) cylinder. All spectacle and contact lenses would be made in minus cylinder.

  5. Aspheric lens - Wikipedia

    en.wikipedia.org/wiki/Aspheric_lens

    A profile gauge probe is used to measure a section across the lens surface. The rotation symmetry of the lenses means that the combination of several of these profiles provides a sufficiently precise knowledge of the shape of the lens. Any damage to the lens surface caused by the probe tip would be removed in subsequent steps. [6]

  6. Astigmatism (optical systems) - Wikipedia

    en.wikipedia.org/wiki/Astigmatism_(optical_systems)

    Astigmatism causes difficulties in seeing fine detail. Astigmatism can be often corrected by glasses with a lens that has different radii of curvature in different planes (a cylindrical lens), contact lenses, or refractive surgery. [5] Astigmatism is quite common. Studies have shown that about one in three people suffers from it.

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