Search results
Results from the WOW.Com Content Network
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 ...
The following are lists of devices categorized as types of telescopes or devices associated with telescopes.They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types.
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 Gauss lens is a compound achromatic lens that uses two uncemented elements; in its most basic form, a positive meniscus lens on the object side and a negative meniscus lens on the image side.
An f /6 achromatic refractor is likely to show considerable color fringing (generally a purple halo around bright objects); an f / 16 achromat has much less color fringing. In very large apertures, there is also a problem of lens sagging, a result of gravity deforming glass. Since a lens can only be held in place by its edge, the center of a ...
The achromatic number ψ(G) of a graph G is the maximum number of colors possible in any complete coloring of G. A complete coloring is the opposite of a harmonious coloring , which requires every pair of colors to appear on at most one pair of adjacent vertices.
Chester Moore Hall (9 December 1703, Leigh, Essex, England – 17 March 1771, Sutton) was a British lawyer and inventor who produced the first achromatic lenses in 1729 or 1733 (accounts differ). He used the achromatic lens to build the first achromatic telescope , a refracting telescope free from chromatic aberration (colour distortion).
This was a simple plano-convex or bi-convex lens, or sometimes a combination of lenses. With the development of the modern achromatic objective in 1829, by Joseph Jackson Lister, the need for better condensers became increasingly apparent. By 1837, the use of the achromatic condenser was introduced in France, by Felix Dujardin, and Chevalier.