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Joseph Fraunhofer (6 March 1787 – 7 June 1826), ennobled in 1824 as Ritter von Fraunhofer, was a German optician. He is known for discovering the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives. ==Biography== Joseph Fraunhofer was born in Straubing, Bavaria, to Franz Xaver Fraunhofer and Maria Anna Frohlich. He became an orphan at the age of 11, and he started working as an apprentice to a harsh glassmaker named Philipp Anton Weichelsberger. In 1801, the workshop in which he was working collapsed and he was buried in the rubble. The rescue operation was led by Maximilian IV Joseph, Prince Elector of Bavaria (the future Maximilian I Joseph). The prince entered Fraunhofer's life, providing him with books and forcing his employer to allow the young Fraunhofer time to study. Joseph Utzschneider was also at the site of the disaster, a fact which turned out to be important. With the money given to him by the Prince upon his rescue and the support he received from Utzschneider, Fraunhofer was able to continue his education alongside his practical training.〔Ralf Kern: Wissenschaftliche Instrumente in ihrer Zeit. Band 4: Perfektion von Optik und Mechanik. Cologne, 2010. 355-356.〕 In 1806 Utzschneider and Georg von Reichenbach then brought Fraunhofer into their Institute at Benediktbeuern, a secularised Benedictine monastery devoted to glass making. There he discovered how to make the world's finest optical glass and invented incredibly precise methods for measuring dispersion. It was at the Institute that Fraunhofer met Pierre Louis Guinand, a Swiss glass technician, who Utzschneider had introduce Fraunhofer to the secrets of glass making.〔 In 1809 the mechanical part of the Optical Institute was chiefly under Fraunhofer's direction, and that same year he became one of the members of the firm. In 1814, Guinand left the firm, as did Reichenbach, and Fraunhofer became a partner in the firm,〔 〕 the name being changed to Utzschneider und Fraunhofer. In 1818, he became the director of the Optical Institute. Due to the fine optical instruments he had developed, Bavaria overtook England as the centre of the optics industry. Even the likes of Michael Faraday were unable to produce glass that could rival Fraunhofer's. His illustrious career eventually earned him an honorary doctorate from the University of Erlangen in 1822. In 1824, he was awarded the Merit Order of the Bavarian Crown (through which he was ennobled), and made an honorary citizen of Munich. Like many glassmakers of his era who were poisoned by heavy metal vapours, Fraunhofer died young, in 1826 at the age of 39. His most valuable glassmaking recipes are thought to have gone to the grave with him. 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「Joseph von Fraunhofer」の詳細全文を読む スポンサード リンク
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