ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY ROYAL ASTRONOMICAL SOCIETY / SCIENCE PHOTO LIBRARY
John Dollond (1706-1761), British scientific instrument maker. Dollond founded an optical business designing and producing telescopes that was to stay in the family for 5 generations. He is credited with the invention of the achromatic lens. This reduced the problem of chromatic aberration in telescopes. This is the inability of a lens to focus all colours or wavelengths of light to the same point, because different wavelengths are differentially refracted by the glass. Dollond produced and patented a lens made of two materials of different dispersion to correct the aberration. He won a medal from the Royal Society for his invention, and even though his patent was later contested, his rights were upheld.
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