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Abbe number. In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is an approximate measure of the material's dispersion (change of refractive index versus wavelength), with high values of V indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist ...
Corrective lens. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
In optics, the Abbe sine condition is a condition that must be fulfilled by a lens or other optical system in order for it to produce sharp images of off-axis as well as on-axis objects. It was formulated by Ernst Abbe in the context of microscopes. [1] The Abbe sine condition says that. the sine of the object-space angle should be proportional ...
Number ones. The Bee Gees scored the most number-one hits (9 songs) and had the longest cumulative run atop the Billboard Hot 100 chart (27 weeks) during the 1970s. Rod Stewart remained at the top of the Billboard Hot 100 chart for 17 weeks during the 1970s. Elton John amassed the second-most number-one hits on the Hot 100 chart during the ...
An optical instrument is said to be diffraction-limited if it has reached this limit of resolution performance. Other factors may affect an optical system's performance, such as lens imperfections or aberrations, but these are caused by errors in the manufacture or calculation of a lens, whereas the diffraction limit is the maximum resolution ...
Abbe condensers are difficult to use for magnifications of above 400X, as the aplanatic cone is only representative of a numerical aperture (NA) of 0.6. This condenser is composed of two lenses, a plano-convex lens somewhat larger than a hemisphere and a large bi-convex lens serving as a collecting lens to the first.
The links on this page contain lists of songs that have reached number-one on the Billboard adult contemporary chart. This chart was first printed in Billboard magazine in 1961 and lists the most popular songs as determined by airplay on American adult contemporary music radio stations. Over the years, the chart has gone by a variety of names ...
Polydor Records. 1979. Erlewine, Stephen Thomas. "Quadrophenia [Music from the Soundtrack of The Who Film] - The Who". AllMusic. Retrieved 18 March 2020. ^ a b Two's Missing: Two's Missing (liner notes). The Who. MCA Records. 1987.