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An Achromatic telescope uses an achromatic lens to correct for this. An achromatic lens is a compound lenses made with two types of glass with different dispersion. One element, a concave lens made out of Flint glass, has relatively high dispersion, while the other, a convex element made of Crown glass, has a lower dispersion. The crown lens is ...
It was first proposed in 1817 by the mathematician Carl Friedrich Gauss for a refracting telescope design, but was seldom implemented and is better known as the basis for the Double-Gauss lens first proposed in 1888 by Alvan Graham Clark, which is a four-element, four-group compound lens that uses a symmetric pair of Gauss lenses.
Telescopes can be classified by optical design or mechanical design/construction. Telescopes can also be classified by where they are placed, such as space telescopes . One major determining factor is type of light, or particle being observed including devices referred to as "telescopes" that do not form an image or use optics.
Cone of light behind an achromatic doublet objective lens (A) without (red) and with (green) a Barlow lens optical element (B). The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system.
Joseph Ritter von Fraunhofer (/ ˈ f r aʊ n ˌ h oʊ f ər /; German: [ˈfraʊnˌhoːfɐ]; 6 March 1787 – 7 June 1826 [1]) was a German physicist and optical lens manufacturer. He made optical glass, an achromatic telescope, and objective lenses. He developed diffraction grating and also invented the spectroscope.
In optics, one important and familiar consequence of dispersion is the change in the angle of refraction of different colors of light, [2] as seen in the spectrum produced by a dispersive prism and in chromatic aberration of lenses. Design of compound achromatic lenses, in which chromatic aberration is largely cancelled, uses a quantification ...
It can be further minimized by using an achromatic lens or achromat, in which materials with differing dispersion are assembled together to form a compound lens. The most common type is an achromatic doublet , with elements made of crown and flint glass .
An achromatic doublet brings red and blue light to the same focus, and is the earliest example of an achromatic lens. In an achromatic lens, two wavelengths are brought into the same focus, here red and blue. An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses ...