John Dollond
John Dollond ( born June 10, 1706 Spitalfields, London, † November 30, 1761 in London) was a British optician and telescope builders of French origin.
Life
He came from a Huguenot immigrant family and was initially like everyone else in his family worked as silk weavers, but dealt with alongside astronomy and optics. Later he founded a workshop for the manufacture of optical and astronomical equipment. Since 1752, he worked with his son Peter ( 1730-1820 ) in London at the improvement of dioptric telescopes to their chromatic aberration - to decrease - the disturbing color fringes.
After several attempts in the years 1757 and 1758, which had inspired him the researches of Samuel Klingenstierna, he discovered the unequal refraction of the colored rays of light in glass prisms of various powers. He concluded the possibility of producing achromatic lenses, which should show color pictures alone.
Although Dollond was not the inventor of this breakthrough innovation in Fernrohrbau - the actual invention of the achromatic succeeded Chester Moor Hall, however, was not interested in the commercial exploitation of his invention. But Dollond was the first and for many years only one who could make these lenses economically. Dollond in 1758 was honored by the Royal Society with the Copley Medal. In the same year he was granted a patent to 14 years for the manufacture of achromatic lenses.
The high quality of Dollonds flint glass lenses goes back to the purchase of a very good successful melt from Northern England. In addition to its largest lens of 5 inches (12.7 cm) emerged at Dollonds lifetime about a dozen with an opening of 4 inches (about 10 cm). Only 20 years later, for example, is estimated the aspiring astronomer Johann Hieronymus Schroeter happy to be able to acquire such a refracting telescope.
John Dollond died on November 30, 1761 in London. His eldest son, Peter Dollond, divided the scientific interests of his father, and later founded an optical institute. Peter Dollond invented the apochromat.