Aperture
Historical document, translated for reference.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 Great Medical Encyclopedia defines aperture as a key value characterizing optical systems. It explains its mathematical formula based on the refractive index and the angle of the ray cone, and notes its direct proportionality to microscope image brightness.
Encyclopedia entry (1928–1936)
APERTURE (from Latin apertus - open), a value that characterizes an optical system and is of great importance in evaluating the quality of such a system. The aperture is equal to the product of the refractive index of the medium in which the object under consideration is located, and the sine of the angle formed by the generators of the cone of rays surface with the optical axis of the instrument. At a given microscope magnification, the brightness of the image is directly proportional to the square of the aperture.
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Cite this page
“Aperture.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/aperture/