John Dollond

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John Dollond

John Dollond (born June 10, 1706 in Spitalfields , London, †  November 30, 1761 in London ) was a British optician and telescope maker of French origin.


He came from a Huguenot emigrant family and initially worked as a silk weaver like everyone in his family , but also dealt with astronomy and optics . He later founded a workshop for the manufacture of optical and astronomical devices. From 1752 he worked with his son Peter (1730-1820) in London on the improvement of dioptric telescopes in order to reduce their chromatic aberration - the annoying color fringes.

After several attempts in the years 1757 and 1758, to which the investigations of Samuel Klingenstierna had inspired him, he discovered the unequal refraction of colored light rays in glass prisms of different refractive powers . From this he deduced the possibility of producing achromatic lenses that should show images of pure color.

Dollond was not the inventor of this groundbreaking innovation in telescope construction - the actual invention of the achromatic lens was made by Chester Moor Hall , who was not interested in the commercial use of his invention. But Dollond was the first, and for years the only one, who could manufacture these lenses economically. In 1758 Dollond was awarded the Copley Medal by the Royal Society . In the same year he was granted a 14-year patent for the production of the achromatic lenses. He shared the proceeds from it with Francis Watkins, who had financed it.

The high quality of Dollond's flint glass lenses can be traced back to the purchase of an extremely successful melt from northern England. In addition to his largest lens of 5 inches (12.7 cm), about a dozen with an aperture of 4 inches (about 10 cm) were made during Dollond's lifetime. 20 years later, z. For example, the aspiring astronomer Johann Hieronymus Schroeter was happy to acquire such a lens telescope.

John Dollond died in London on November 30, 1761. His eldest son, Peter Dollond , shared his father's scientific interests and later founded an optical institute. Peter Dollond invented the apochromat .

His son-in-law was the optician Jesse Ramsden , to whom, according to some sources, he also gave the patent for achromatic glasses as a dowry from his youngest daughter Sarah (1743–1796).

The Dollond crater is named after him.


Web links

Commons : John Dollond  - album with pictures, videos and audio files

Individual evidence

  1. Anita McConnel Jesse Ramsden , Ashgate Publ., 2007, p. 17