The Search Engine Google is showing an animated Doodle in few Countries for the Ferdinand Monoyer’s 181st Birthday
Ferdinand Monoyer was a French ophthalmologist, known for introducing the dioptre in 1872.
A dioptre is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres.
The main benefit of using optical power rather than focal length is that the lensmaker’s equation has the object distance, image distance, and focal length all as reciprocals. A further benefit is that when relatively thin lenses are placed close together their powers approximately add. Thus, a thin 2-dioptre lens placed close to a thin 0.5-dioptre lens yields almost the same focal length as a 2.5-dioptre lens would have.
Ferdinand Monoyer was born in France on May 9, 1836.
Monoyer was of Alsatian heritage by his mother and was the son of a French military doctor. He was an Associate Professor of Medical Physics at the Faculty of Medicine of the University of Strasbourg in 1871. Later, he was director of the Ophthalmic Clinic of the Faculty of Medicine, University of Nancy from 1872-1877. He was also Professor of medical physics at the Faculty of Medicine at the University of Lyon from 1877-1909.
Ferdinand Monoyer also invented the Monoyer chart, used to test visual acuity.
He inserted his name in the chart; People can read his name by reading vertically from bottom to top on each side of the chart