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  2. 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 ...

  3. f-number - Wikipedia

    en.wikipedia.org/wiki/F-number

    f-number. Diagram of decreasing apertures, that is, increasing f-numbers, in one-stop increments; each aperture has half the light-gathering area of the previous one. An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the ...

  4. Cardinal point (optics) - Wikipedia

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

    For a single lens surrounded by a medium of refractive index n = 1, the locations of the principal points H and H ′ with respect to the respective lens vertices are given by the formulas = ′ = (), where f is the focal length of the lens, d is its thickness, and r 1 and r 2 are the radii of curvature of its surfaces. Positive signs indicate ...

  5. Magnification - Wikipedia

    en.wikipedia.org/wiki/Magnification

    Magnification. Process of enlarging the apparent size of something. The postage stamp appears larger with the use of a magnifying glass. Stepwise magnification by 6% per frame into a 39-megapixel image. In the final frame, at about 170x, an image of a bystander is seen reflected in the man's cornea. Magnification is the process of enlarging the ...

  6. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    To focus an object 1 m away (s 1 = 1,000 mm), the lens must be moved 2.6 mm farther away from the film plane, to s 2 = 52.6 mm. The focal length of a lens determines the magnification at which it images distant objects. It is equal to the distance between the image plane and a pinhole that images distant objects the same size as the lens in ...

  7. Angular aperture - Wikipedia

    en.wikipedia.org/wiki/Angular_aperture

    The angular aperture of a thin lens with focal point at F and an aperture of diameter . The angular aperture of a lens is the angular size of the lens aperture as seen from the focal point: where. f {\displaystyle f} is the focal length.

  8. Angular resolution - Wikipedia

    en.wikipedia.org/wiki/Angular_resolution

    Angular resolution. A series of images representing the magnification of M87* with an angular size of some microarcseconds, comparable to viewing a tennis ball on the Moon (magnification from top left corner counter−clockwise to the top right corner). Angular resolution describes the ability of any image-forming device such as an optical or ...

  9. Optical microscope - Wikipedia

    en.wikipedia.org/wiki/Optical_microscope

    Optical microscope. The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century.