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  2. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    Focal length. The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a ...

  3. List of longest smartphone telephoto lenses - Wikipedia

    en.wikipedia.org/wiki/List_of_longest_smartphone...

    List of longest smartphone telephoto lenses. This is a list of smartphones with a telephoto lens that offers a focal length (35mm equivalent) of at least 100mm or "4× optical zoom" with an imaging area equivalent to a 1/3.5″ or larger sensor. Smartphone lenses are often marketed in terms of "optical zoom" [1] relative to the phone's main camera.

  4. Optical path length - Wikipedia

    en.wikipedia.org/wiki/Optical_path_length

    Optical path length. In optics, optical path length (OPL, denoted Λ in equations), also known as optical length or optical distance, is the length that light needs to travel through a vacuum to create the same phase difference as it would have when traveling through a given medium. It is calculated by taking the product of the geometric length ...

  5. 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 ...

  6. Numerical aperture - Wikipedia

    en.wikipedia.org/wiki/Numerical_aperture

    The numerical aperture with respect to a point P depends on the half-angle, θ1, of the maximum cone of light that can enter or exit the lens and the ambient index of refraction. As a pencil of light goes through a flat plane of glass, its half-angle changes to θ2. Due to Snell's law, the numerical aperture remains the same: NA = n1 sin θ1 ...

  7. Sagitta (optics) - Wikipedia

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

    Sagitta (optics) Deep blue ray refers the radius of curvature and the red line segment is the sagitta of the curve (black). In optics and especially telescope making, sagitta or sag is a measure of the glass removed to yield an optical curve. It is approximated by the formula. where R is the radius of curvature of the optical surface.

  8. Calculation of glass properties - Wikipedia

    en.wikipedia.org/wiki/Calculation_of_glass...

    The calculation of glass properties allows "fine-tuning" of desired material characteristics, e.g., the refractive index. [1]The calculation of glass properties (glass modeling) is used to predict glass properties of interest or glass behavior under certain conditions (e.g., during production) without experimental investigation, based on past data and experience, with the intention to save ...

  9. 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.