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  2. Lens - Wikipedia

    en.wikipedia.org/wiki/Lens

    A lens with one convex and one concave side is convex-concave or meniscus. Convex-concave lenses are most commonly used in corrective lenses, since the shape minimizes some aberrations. For a biconvex or plano-convex lens in a lower-index medium, a collimated beam of light passing through the lens converges to a spot (a focus) behind

  3. Focal length - Wikipedia

    en.wikipedia.org/wiki/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.

  4. Vergence (optics) - Wikipedia

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

    For concave lenses, the focal point is on the back side of the lens, or the output side of the focal plane, and is negative in power. A lens with no optical power is called an optical window, having flat, parallel faces. The optical power directly relates to how large positive images will be magnified, and how small negative images will be ...

  5. Real image - Wikipedia

    en.wikipedia.org/wiki/Real_image

    Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted. As the object approaches the focal point the image approaches infinity, and when the object passes the focal point the image becomes virtual and is not ...

  6. Optical flat - Wikipedia

    en.wikipedia.org/wiki/Optical_flat

    A ring of concentric circles can indicate that the surface is either concave or convex, which is an effect similar to the hollow-mask illusion. There are three ways to test the surface for shape, but the most common is the "finger-pressure test." In this test, slight pressure is applied to the flat, to see which way the fringes move.

  7. Dispersion staining - Wikipedia

    en.wikipedia.org/wiki/Dispersion_staining

    The Becke' Line method takes advantage of the fact that particles behave basically like lenses because they tend to be thinner at the edges than they are at the center. If the particle has a higher refractive index than the liquid surrounding it then it behaves as a convex lens and focuses a parallel beam of light on the side opposite the ...

  8. Geometrical optics - Wikipedia

    en.wikipedia.org/wiki/Geometrical_optics

    Thin lenses produce focal points on either side that can be modeled using the lensmaker's equation. [5] In general, two types of lenses exist: convex lenses, which cause parallel light rays to converge, and concave lenses, which cause parallel light rays to diverge. The detailed prediction of how images are produced by these lenses can be made ...

  9. Center of curvature - Wikipedia

    en.wikipedia.org/wiki/Center_of_curvature

    A concave mirror with light rays Center of curvature. In geometry, the center of curvature of a curve is a point located at a distance from the curve equal to the radius of curvature lying on the curve normal vector. It is the point at infinity if the curvature is zero. The osculating circle to the curve is centered at the centre of curvature.