Dioptre
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
This article from the 1928-1936 Soviet Great Medical Encyclopedia defines the dioptre as the unit of refractive power of a lens or optical system. It explains the historical development of measuring optical power based on focal length and older units of measurement.
Encyclopedia entry (1928–1936)
DIOPTRE, the unit of refractive power of a lens or optical system. The refractive power is greater the shorter the focal distance of the lens; formerly, the optical power of a lens was also designated by the length of its focal distance. Initially, a glass with a focal distance of 1 inch was adopted as the unit (No. 1). A lens with a focal distance of 2 inches (No. 2) refracted twice
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Cite this page
“Dioptre.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/dioptre/