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A reflecting telescope (also called a reflector) is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Reflecting telescopes come in many design variations and may employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a "catoptric" telescope. ==History== (詳細はcurved mirrors behave like lenses dates back at least to Alhazen's 11th century treatise on optics, works that had been widely disseminated in Latin translations in early modern Europe.〔(Stargazer - By Fred Watson, Inc NetLibrary, Page 108 )〕 Soon after the invention of the refracting telescope, Galileo, Giovanni Francesco Sagredo, and others, spurred on by their knowledge of the principles of curved mirrors, discussed the idea of building a telescope using a mirror as the image forming objective.〔(Stargazer - By Fred Watson, Inc NetLibrary, Page 109 )〕 There were reports that the Bolognese Cesare Caravaggi had constructed one around 1626 and the Italian professor Niccolò Zucchi, in a later work, wrote that he had experimented with a concave bronze mirror in 1616, but said it did not produce a satisfactory image.〔(Stargazer By Fred Watson, Inc NetLibrary Page 109 )〕 The potential advantages of using parabolic mirrors, primarily reduction of spherical aberration with no chromatic aberration, led to many proposed designs for reflecting telescopes〔theoretical designs by Bonaventura Cavalieri, Marin Mersenne, and Gregory among others〕 the most notable being James Gregory’s 1663 published ideas for what came to be called the Gregorian telescope,〔(Stargazer - By Fred Watson, Inc NetLibrary, Page 117 )〕〔(The History of the Telescope By Henry C. King, Page 71 )〕 but no working models were built until 1673 by Robert Hooke. Isaac Newton has been generally credited with building the first reflecting telescope in 1668.〔(Isaac Newton: adventurer in thought, by Alfred Rupert Hall, page 67 )〕 It used a spherically ground metal primary mirror and a small diagonal mirror in an optical configuration that has come to be known as the Newtonian telescope. Despite the theoretical advantages of the reflector design, the difficulty of construction and the poor performance of the speculum metal mirrors being used at the time meant it took over 100 years for them to become popular. Many of the advances in reflecting telescopes included the perfection of parabolic mirror fabrication in the 18th century,〔Parabolic mirrors were used much earlier, but James Short perfected their construction. See (【引用サイトリンク】title=Reflecting Telescopes (Newtonian Type) )〕 silver coated glass mirrors in the 19th century, long-lasting aluminum coatings in the 20th century,〔Silvering on a reflecting telescope was introduced by Léon Foucault in 1857, see ( madehow.com - Inventor Biographies - Jean-Bernard-Léon Foucault Biography (1819-1868) ), and the adoption of long lasting aluminized coatings on reflector mirrors in 1932. (Bakich sample pages Chapter 2, Page 3 ''"John Donavan Strong, a young physicist at the California Institute of Technology, was one of the first to coat a mirror with aluminum. He did it by thermal vacuum evaporation. The first mirror he aluminized, in 1932, is the earliest known example of a telescope mirror coated by this technique."'' )〕 segmented mirrors to allow larger diameters, and active optics to compensate for gravitational deformation. A mid-20th century innovation was catadioptric telescopes such as the Schmidt camera, which use both a spherical mirror and a lens (called a corrector plate) as primary optical elements, mainly used for wide-field imaging without spherical aberration. The late 20th century has seen the development of adaptive optics and lucky imaging to overcome the problems of seeing, and reflecting telescopes are ubiquitous on space telescopes and many types of spacecraft imaging devices. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reflecting telescope」の詳細全文を読む スポンサード リンク
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