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Ernst Karl Abbe (23 January 1840 – 14 January 1905), was a German businessman, optical engineer, physicist, and social reformer. Together with Otto Schott and Carl Zeiss, he developed numerous optical instruments. He was also a co-owner of Carl Zeiss AG, a German manufacturer of scientific microscopes, astronomical telescopes, planetariums, and other advanced optical systems.
Abbe was the first to define the term numerical aperture, as the sine of the half angle multiplied by the refractive index of the medium filling the space between the cover glass and front lens.
Abbe is credited by many for discovering the resolution limit of the microscope, and the formula (published in 1873)
although in a publication in 1874, Helmholtz states this formula was first derived by Joseph Louis Lagrange, who had died 61 years prior. Helmholtz was so impressed as to offer Abbe a professorship at the University of Berlin, which he declined because of his ties to Zeiss. Abbe was in the camp of the wide aperturists, arguing that microscopic resolution is ultimately limited by the aperture of the optics, but also argued that depending on application there are other parameters that should be weighted over the aperture in the design of objectives. In Abbe's 1874 paper, titled "A Contribution to the Theory of the Microscope and the nature of Microscopic Vision", Abbe states that the resolution of a microscope is inversely dependent on its aperture, but without proposing a formula for the resolution limit of a microscope.
In 1876, Abbe was offered a partnership by Zeiss and began to share in the considerable profits. Although the first theoretical derivations of were published by others, it is fair to say that Abbe was the first to reach this conclusion experimentally. In 1878, he built the first homogenous immersion system for the microscope. The objectives that the Abbe Zeiss collaboration were producing were of ideal ray geometry, allowing Abbe to find that the aperture sets the upper limit of microscopic resolution, not the curvature and placement of the lenses. Abbe's first publication of occurred in 1882. In this publication, Abbe states that both his theoretical and experimental investigations confirmed . Abbe's contemporary Henry Edward Fripp, English translator of Abbe's and Helmholtz's papers, puts their contributions on equal footing. He also perfected the interference method by Fizeau, in 1884. Abbe, Zeiss, Zeiss' son, Roderich Zeiss, and Otto Schott formed, in 1884, the Schott AG. This company, which in time would in essence merge with Zeiss Optical Works, was responsible for research and production of 44 initial types of optical glass. Working with , he built an image reversal system in 1895.
In order to produce high quality objectives, Abbe made significant contributions to the diagnosis and correction of optical aberrations, both spherical aberration and coma aberration, which is required for an objective to reach the resolution limit of . In addition to spherical aberration, Abbe discovered that the rays in optical systems must have constant angular magnification over their angular distribution to produce a diffraction limited spot, a principle known as the Abbe sine condition. So monumental and advanced were Abbe's calculations and achievements that Frits Zernike based his phase contrast work on them, for which he was awarded the Nobel Prize in 1953, and Hans Busch used them to work on the development of the electron microscope.
During his association with Carl Zeiss' microscope works, not only was he at the forefront of the field of optics but also labor reform. He founded the social democratic Jenaische Zeitung (newspaper) in 1890 and in 1900, introduced the eight-hour workday, in remembrance of the 14-hour workday of his own father. In addition, he created a pension fund and a discharge compensation fund. In 1889, Ernst Abbe set up and endowed the Carl Zeiss Foundation for research in science. The aim of the foundation was "to secure the economic, scientific, and technological future and in this way to improve the job security of their employees." He made it a point that the success of an employee was based solely on their ability and performance, not on their origin, religion, or political views. In 1896, he reorganized the Zeiss optical works into a cooperative with profit-sharing. His social views were so respected as to be used by the state as a model and idealized by Alfred Weber in the 1947 book Schriften der Heidelberger Aktionsgruppe zur Demokratie und Zum Freien Sozialismus ( Writings of the Heidelberg Action Group on Democracy and Free Socialism).
The crater Abbe on the Moon was named in his honour.
Bibliography
Abbe was a pioneer in optics, lens design, and microscopy, and an authority of his time. He left us with numerous publications of his findings, inventions, and discoveries. Below is a list of publications he authored including many links to the scanned Google Books pages.
See also
Notes
Sources
Joint Committee of Civil Engineers (1994). 9780784400500, American Society of Civil Engineers. ISBN 9780784400500
Further reading
External links
Categories: 1840 Births, 1905 Deaths, 19th-century German Businesspeople, 19th-century German Inventors, 19th-century German Physicists, Academic Staff Of The University Of Jena, Carl Zeiss Ag People, Fellows Of The Royal Microscopical Society, German Atheists, German Businesspeople In Manufacturing, German Scientific Instrument Makers, History Of Glass, Glass Engineering And Science, Glass Physics, Lens Designers, Members Of The Göttingen Academy Of Sciences And Humanities, Members Of The Prussian Academy Of Sciences, Microscopists, Optical Engineers, People From Eisenach, People From Saxe-weimar-eisenach, University Of Göttingen Alumni, University Of Jena Alumni
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