Online articles on optics and telescope design

Перспективы развития кассегреновских телескопов с корректором в сходящихся пучках лучей

Ю.А.Клевцов, канд. техн. наук: Проанализированы пути и перспективы развития телескопов с корректором в сходящихся пучках лучей. Выделены основные типы систем со сферической оптикой, пригодные для разработки на их основе серийных телескопов с небольшим действующим отверстием. Подробно разбираются достоинства и недостатки таких телескопов. Рассмотрены принципы построения оптических систем кассегреновских телескопов с менисковым корректором в качестве вторичного отражательного элемента. Детально проанализированы характерные особенности и история разработки отдельных типов этих систем. Намечены перспективы дальнейшего развития таких телескопов и обосновывается ниша их возможного применения в наблюдательной астрономии.
More detail: [in Rusian>>]

New optical systems for small-size telescopes

Yu. A. Klevtsov: The deficiencies of the popular mass-produced telescopes of the Schmidt-Cassegrain design include their low aperture ratio and narrow spectral range. The novel systems for Cassegrain telescopes with a meniscus corrector proposed here are free of these deficiencies. Two such systems are described: a system with corrector lenses made from the same material and a system with corrector lenses made from different materials. The systems are technologically convenient (all the surfaces are spherical) and are distinguished by small lens diameters (down to 1/3 of the effective aperture), compactness, a high aperture ratio (up to 1:6.5-1:7), high-quality aberration correction, and a broad spectral range (400-900 nm), which is sufficient for working with modern photographic materials and CCD arrays.
More detail: [in English>>] [in German>>] [in Russian>>]

Top Ten TALScopes Myths

Bill Brady: 1. TAL mounts are junk. FALSE. TAL mounts are built the old fashioned way, with massive solid steel shafts and preloaded ball bearings on the worm and RA shafts. The larger GEM also has preloaded ball bearings on the Declination shaft. The TAL mounts do need adjustment, they have no springs or plastic thrust bearing parts to take up the slack. With periodic adjustment and lubrication, they will last a lifetime.
More detail: [at Yahoo! groups>>] [at this website>>]

A compact short-focus telescope with spherical optical surfaces

Robert J. Magee: The optical system consists of a perforated primary mirror, a two-element corrector lens (with one surface aluminized to function as the secondary mirror), a diagonal mirror and the eyepiece. The small two-element corrector lens replaces the full-aperture lens of the popular Maksutov system. The combination of an achromatic lens and a second-surface mirror that I use is known as a Mangin mirror. [More detail>>]

Maksutovs with Subaperture Correctors

Australian amateur Ralph W. Field, after completing the design calculations presented in this article, begins to grind the small meniscus corrector for a working telescope. [More detail>>]

A Telescope-Making Tradition in Russia

Sergey Maslikov: The first Russian-made astronomical optic was probably crafted by Jacob Bryus, a member of Peter the Great's inner circle, who fashioned a concave mirror for a reflecting telescope in 1733. But our country's first true amateur telescope maker was Ivan Kulibin. A self-educated mechanic from Nizhny Novgorod, Kulibin managed to get his hands on a Gregorian reflector in 1767. He was able to determine the formula of its speculum-metal mirror - a hard, brittle alloy of copper and tin - and he proceeded to build a machine for grinding and polishing mirrors and lenses. Kulibin also crafted flint glass for making achromatic objective lenses. [More detail>>]

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