John Dollond

John Dollond FRS (10 June O.S. (21 June N.S.) 1706 - 30 November 1761) was an English optician, known for his successful optics business and his patenting and commercialization of achromatic doublets.

Biography

Dollond was the son of a Huguenot refugee, a silk-weaver at Spitalfields, London, where he was born. He followed his father's trade, but found time to acquire a knowledge of Latin, Greek, mathematics, physics, anatomy and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond (1730–1820), who in 1750 had started in business as a maker of optical instruments; this business is now Dollond & Aitchison. His reputation grew rapidly, and in 1761 he was appointed optician to the king.

In 1758 he published an "Account of some experiments concerning the different refrangibility of light" (Phil. Trans., 1758), describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lenses by the combination of crown and flint glasses, which reduces chromatic aberration (color defects). Leonhard Euler in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. Relying on statements made by Sir Isaac Newton, Dollond disputed this possibility (Phil. Trans., 1753), but subsequently, after the Swedish physicist, Samuel Klingenstierna (1698–1765), had pointed out that Newton's law of dispersion did not harmonize with certain observed facts, he began experiments to settle the question.