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Ernst Abbe

From Wikipedia, the free encyclopedia
(Redirected fromErnst Karl Abbe)
German physicist, entrepreneur, and social reformer (1840–1905)

Ernst Abbe
Born(1840-01-23)23 January 1840
Died14 January 1905(1905-01-14) (aged 64)
Alma mater
Known for
Scientific career
FieldsPhysics
Optical engineering
InstitutionsUniversity of Jena
Doctoral advisor
Doctoral studentsHeinrich Friedrich Weber
Other notable studentsGottlob Frege

Ernst Karl AbbeHonFRMS (23 January 1840 – 14 January 1905), was a German businessman, optical engineer, physicist, and social reformer. Together withOtto Schott andCarl Zeiss, he developed numerous optical instruments. He was also a co-owner ofCarl Zeiss AG, a German manufacturer of scientific microscopes, astronomical telescopes, planetariums, and other advanced optical systems.

Personal life

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Else Snell

Abbe was born 23 January 1840 inEisenach,Saxe-Weimar-Eisenach,[1] to Georg Adam Abbe and Elisabeth Christina Barchfeldt.[2] He came from a humble home – his father was a foreman in a spinnery. Supported by his father's employer, Abbe was able to attend secondary school and to obtain the general qualification for university entrance with fairly good grades, at the Eisenach Gymnasium, which he graduated from in 1857.[3] By the time he left school, his scientific talent and his strong will had already become obvious. Thus, in spite of the family's strained financial situation, his father decided to support Abbe's studies at the Universities ofJena (1857–1859) andGöttingen (1859–1861).[1] During his time as a student, Abbe gave private lessons to improve his income. His father's employer continued to fund him. Abbe was awarded hisPhD in Göttingen on 23 March 1861.[3] While at school, he was influenced byBernhard Riemann andWilhelm Eduard Weber, who also happened to be one of theGöttingen Seven.[4] This was followed by two short assignments at the Göttingenobservatory and at Physikalischer Verein inFrankfurt (an association of citizens interested in physics and chemistry that was founded byJohann Wolfgang von Goethe in 1824 and still exists today).[4] On 8 August 1863 he qualified as a university lecturer at the University of Jena. In 1870, he accepted a contract as an associateprofessor of experimentalphysics,mechanics andmathematics in Jena.[1][5] In 1871, he married Else Snell, daughter of the mathematician and physicist Karl Snell, one of Abbe's teachers,[nb 1] with whom he had two daughters.[2] He attained full professor status by 1879.[2] He became director of theJena astronomical and meteorological observatory in 1878.[5][nb 2] In 1889, he became a member of theBavarian Academy of Sciences and Humanities. He also was a member of the Saxon Academy of Sciences. He was relieved of his teaching duties at the University of Jena in 1891. Abbe died 14 January 1905 in Jena.[1] He was an atheist.[6]

Life work

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Microscope by Carl Zeiss (1879) with optics by Abbe
The resolution limit formula engraved in an Ernst Abbe memorial in Jena, Germany
Ernst Abbe, relief at his grave

In 1866, he became a research director at theZeiss Optical Works, and in 1868 he invented theapochromatic lens, a microscope lens which eliminates both the primary and secondary color distortion.[5] By 1870, Abbe invented theAbbe condenser, used for microscope illumination.[5] In 1871, he designed the firstrefractometer, which he described in a booklet published in 1874.[2][7] He developed the laws of image of non-luminous objects by 1872.[2] Zeiss Optical Works began selling his improved microscopes in 1872, including models with homogenous immersion objective by 1877 and his apochromatic objective microscopes in 1886.[8] He created theAbbe number, a measure of anytransparent material's variation ofrefractive index withwavelength and Abbe's criterion, which tests the hypothesis, that a systematic trend exists in a set of observations (in terms of resolving power this criterion stipulates that an angular separation cannot be less than the ratio of the wavelength to the aperture diameter, seeangular resolution).[9] Already a professor inJena, he was hired byCarl Zeiss to improve the manufacturing process of optical instruments, which back then was largely based on trial and error.

Abbe was the first to define the termnumerical aperture,[10] 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)

d=λ2NA{\displaystyle d={\frac {\lambda }{2NA}}}Eq. 1

although in a publication in 1874,[11]Helmholtz states this formula was first derived byJoseph Louis Lagrange, who had died 61 years prior. Helmholtz was so impressed as to offer Abbe a professorship at theUniversity of Berlin, which he declined because of his ties to Zeiss.[4] 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",[12] 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.[4] Although the first theoretical derivations ofEq. 1 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.[2] 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 ofEq. 1 occurred in 1882.[13] In this publication, Abbe states that both his theoretical and experimental investigations confirmedEq. 1. Abbe's contemporary Henry Edward Fripp, English translator of Abbe's and Helmholtz's papers, puts their contributions on equal footing. He also perfected theinterference method byFizeau, in 1884.[2] Abbe, Zeiss, Zeiss' son,Roderich Zeiss, andOtto Schott formed, in 1884, theJenaer Glaswerk Schott & Genossen. 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.[8] Working withtelescopes, he built an image reversal system in 1895.[2]

In order to produce high quality objectives, Abbe made significant contributions to the diagnosis and correction ofoptical aberrations, bothspherical aberration andcoma aberration, which is required for an objective to reach the resolution limit ofEq. 1. 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 theAbbe sine condition.[10] So monumental and advanced were Abbe's calculations and achievements thatFrits Zernike based hisphase contrast work on them, for which he was awarded theNobel Prize in 1953, andHans Busch used them to work on the development of theelectron microscope.[4]

During his association withCarl Zeiss'microscope works, not only was he at the forefront of the field of optics but also labor reform. He founded thesocial democratic Jenaische Zeitung (newspaper) in 1890[14] and in 1900, introduced theeight-hour workday, in remembrance of the 14-hour workday of his own father.[8] In addition, he created a pension fund and a discharge compensation fund.[2] In 1889, Ernst Abbe set up and endowed theCarl Zeiss Foundation for research in science.[2] 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."[8] 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.[8] In 1896, he reorganized the Zeiss optical works into a cooperative with profit-sharing.[5] His social views were so respected as to be used by thePrussian state as a model and idealized byAlfred Weber in the 1947 bookSchriften der Heidelberger Aktionsgruppe zur Demokratie und Zum Freien Sozialismus (Writings of the Heidelberg Action Group on Democracy and Free Socialism).[15]

The craterAbbe on theMoon was named in his honour.[16]

Bibliography

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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

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Notes

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  1. ^Some sources give his wife's name as Elisabeth.[2]
  2. ^The dates of his job appointments at the University of Jena, including his appointment as director of the Jena Observatory has some uncertainty, as sources give different dates, as following. 1870: assistant lecturer on mechanics and experimental physics; 1873: associate professor; 1877: director of the Jena Observatory meteorological and astronomy departments.[2]

References

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  1. ^abcdBlasius 1953, pp. 2–3
  2. ^abcdefghijklDebus et al. 1968, p. 2
  3. ^abGünther 1970, p. 6
  4. ^abcdeGünther 1970, p. 7
  5. ^abcdeHoiberg 2010, p. 11
  6. ^Joseph McCabe (1945). A Biographical Dictionary of Ancient, Medieval, and Modern Freethinkers. Haldeman-Julius Publications. Retrieved 7 April 2013. He was not only a distinguished German physicist and one of the most famous inventors on the staff at the Zeiss optical works at Jena but a notable social reformer, By a generous scheme of profit-sharing he virtually handed over the great Zeiss enterprise to the workers. Abbe was an intimate friend of Haeckel and shared his atheism (or Monism). Leonard Abbot says in his life of Ferrer that Abbe had "just the same ideas and aims as Ferrer."
  7. ^Abbe 1874
  8. ^abcdePfeiffer 1991, p. 445
  9. ^Joint Committee of Civil Engineers, American Congress on Surveying and Mapping & American Society for Photogrammetry and Remote Sensing 1994
  10. ^abAbbe 1881
  11. ^Helmholtz & Fripp 1876
  12. ^Abbe 1876
  13. ^Abbe 1883
  14. ^Walter, Rolf (1996).Carl Zeiss: Zeiss 1905–1945 (in German). Böhlau Verlag. p. 25.ISBN 978-3-412-11096-3.
  15. ^Günther 1970, p. 9
  16. ^"Abbe".Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.

Sources

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Further reading

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  • Sella, Andrea (November 2008)."Abbé's refractometer".Royal Society of Chemistry. Chemistry World. p. 67.Archived from the original on 24 September 2015. Retrieved6 May 2015.
  • Volkmann, Harald. "Ernst Abbe and his work."Applied Optics 5.11 (1966): 1720–1731.

External links

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