Converging lens

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Image formation with a converging lens
The image of a window in the interior of the room under a converging lens (magnifying glass). Objects that are far away (here: the houses) become sharp when the lens is at the distance of its focal length from the projection surface. Strong lenses create small images.

A converging lens , in general and particularly for use in the visible wavelength range, also called a collimator lens , convex lens or positive lens , is a spherically ground lens with positive refractive power . Light incident in parallel is collected in its focal plane . Specifically, light incident parallel to the optical axis is focused at the focal point . For X-ray optics , where materials have a negative refractive power, concave lenses have the property of a converging lens.

The converging lens turns a parallel bundle of light rays into a convergent one, which creates a real image of the surroundings.

Lenses are the most important component of optical systems and are used, for example, for camera lenses , microscope and telescope lenses and the associated eyepieces . The light of different wavelengths is refracted to different degrees by simple glass lenses , which results in imaging errors . This chromatic aberration can be compensated for by combining it with lenses with a different refractive power .

Because of its Fourier transforming properties, the converging lens is also referred to as a Fourier lens .


Types of lenses

Converging lenses can be cast or ground in three shapes: biconvex (curved outwards on both sides), plano-convex (one side flat, the other curved outwards, e.g. with card magnifiers) or concave-convex (one side inward, the other curved outwards).

The latter are also called meniscus lenses (menisci) and are used for most glasses. As a converging lens, they have a cross-section similar to a crescent moon, with the convex side being more curved than the concave (conversely, it would be a diverging lens ). They are often used in multi-lens camera lenses and in compound eyepieces, e.g. B. with the Mittenzwey - and wide angle eyepieces .

Web links

Wiktionary: Collective lens  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Herbert A. Stuart, Gerhard Klages: Short textbook of physics . Springer Verlag, 2016, p. 204 ( limited preview in Google Book search).
  2. B. Lengeler et al .: Imaging by parabolic refractive lenses in the hard X-ray range. In: Journal of Synchrotron Radiation. 1999, No. 6, pp. 1153-1167 ( PDF ).