Ernst Abbe

Personal life

Abbe was born 23 January 1840 in Eisenach, Saxe-Weimar-Eisenach, to Georg Adam Abbe and Elisabeth Christina Barchfeldt. 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. 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 of Jena (1857–1859) and Göttingen (1859–1861). 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 his PhD in Göttingen on 23 March 1861. This was followed by two short assignments at the Göttingen observatory and at Physikalischer Verein in Frankfurt (an association of citizens interested in physics and chemistry that was founded by Johann Wolfgang von Goethe in 1824 and still exists today). In 1871, he married Else Snell, daughter of the mathematician and physicist Karl Snell, one of Abbe's teachers,{{refn|group=nb|Some sources give his wife's name as Elisabeth.

Life work

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 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. 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 Jenaer 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. Working with telescopes, 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.

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.

Notes

References

Sources

References

1. {{harvnb. Blasius. 1953
2. {{harvnb. Debus. Calinger. Collins. Kennedy. 1968
3. {{harvnb. Günther. 1970
4. Günther. 1970
5. Hoiberg. 2010
6. }} with whom he had two daughters. He attained full professor status by 1879. He became director of the [[Jena Observatory|Jena astronomical and meteorological observatory]] in 1878.{{refn|group=nb|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.}} In 1889, he became a member of the [[Bavarian 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. He was an atheist.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. {{harvnb. Joint Committee of Civil Engineers. American Congress on Surveying and Mapping. American Society for Photogrammetry and Remote Sensing. 1994
9. {{harvnb. Abbe. 1881
10. {{harvnb. Helmholtz. Fripp. 1876
11. Walter, Rolf. (1996). "Carl Zeiss: Zeiss 1905–1945". Böhlau Verlag.
12. Günther. 1970
13. {{Gazetteer of Planetary Nomenclature