August Köhler

August Köhler

Infobox_Scientist
name = August Köhler

|300px
caption = August Köhler, ca. 1930
birth_date = birth date|1866|3|4|mf=y
birth_place = Darmstadt, Germany
death_date = death date and age|1948|3|12|1866|3|4|mf=y
death_place = Jena, Germany
residence =
nationality =
field = Physicist
work_institution = University of Giessen
University of Jena
Zeiss Optical Works
alma_mater = University of Heidelberg
University of Giessen
doctoral_advisor = Johann Wilhelm Spengel
doctoral_students =
known_for = Köhler illumination
prizes = honorary doctor degree of the University of Jena
religion =
footnotes =

August Karl Johann Valentin Köhler (1866-1948) was a German professor and early staff member of Zeiss in Jena, Germany. He is best known for his development of the microscopy technique of Köhler illumination, an important principle in optimizing microscopic resolution power by evenly illuminating the field of view. This invention revolutionized light microscope design and is widely used in traditional as well as modern digital imaging techniques today.

Early life and education

Köhler was born in 1866 in Darmstadt, Germany, where he attended the Ludwig-Georgs-Gymnasium until 1884. He studied at the Technical University in Darmstadt and at the universities of Heidelberg and Giessen covering a wide range of fields from zoology and botany to mineralogy, physics, and chemistry. [http://www.zeiss.de/C1256B0500353C49/?Open Zeiss Archives] ]

Teaching and academic career

In 1888, August Köhler graduated with a teaching degree and subsequently taught at gymnasiums in Darmstadt and Bingen before going back to university. He started his academic career as a student, instructor and assistant to professor J.W. Spengel at the Zoological Institute at the University of Giessen, Germany. The object of his doctorate thesis was the taxonomy of limpets, a project that depended heavily on microscopic imaging and prompted Köhler into trying to improve the quality of images taken via photomicrography. The result of this work was published in 1893. [cite journal|author= Köhler A | title = Gedanken zu einem neuen Beleuchtungsverfahren für mikrophotographische Zwecke | journal = Zeitschrift für wissenschaftliche Mikroskopie | date = 1893]

After receiving his doctorate degree from the University of Giessen in 1893, Köhler worked a number of years as a grammar school teacher in Bingen. In 1900, he was invited to join the Zeiss Optical Works company in Jena, Germany, by Siegfried Czapski based on his earlier work on improving microscope illumination. He stayed with Zeiss as a physicist for 45 years and became instrumental to the development of modern light microscope design. From 1922 until his retirement in June 1945, he was also professor for microphotometry at the University of Jena. He became honorary professor of the Medical Faculty at the University of Jena in 1922 and received an honorary medical doctor degree in 1934. In 1938, he assumed the head position for the Department of Microscopy, Microphotography and Projection.

Köhler illumination

At the time of the invention of his revolutionary illumination scheme as a graduate student at the University of Giessen, Köhler was working on overcoming problems with microphotography. Microscopes were illuminated by gas lamps, mirrors or other primitive light sources, resulting in an uneven specimen illumination unsuited for producing good quality photomicrographs using the slow-speed emulsions available at the time. Over the course of his work for his doctorate degree, Köhler developed a microscope configuration that allowed for an evenly illuminated field of view and reduced optical glare from the light source. It involved a collector lens for the lamp that allowed the light source to be focused on the front aperture of the condenser. This in turn allowed the condenser to be focused on the specimen using a field diaphragm and condenser focus control. This superior illumination scheme is still widely used in modern microscopes and forms the basis for phase contrast [cite journal|author= Köhler A, Loos W | title = Das Phasenkontrastverfahren und seine Anwendungen in der Mikroskopie | journal = Naturwissenschaften | date = 1941 | volume = 29 | pages = 49–61 | doi = 10.1007/BF01476460] , differential interference contrast, epifluorescence, and confocal microscopy.Douglas B. Murphy (2001): "Fundamentals of light microscopy and electronic imaging", Wiley-Liss, Inc., New York, ISBN 0-471-25391-X]

Köhler's groundbreaking work on microscope illumination was published in the "Zeitschrift für wissenschaftliche Mikroskopie" in 1893 in Germany, followed by an English summary of his work in the "Journal of the Royal Microscopical Society" one year later. Its significance was not noted until several years later when Köhler was invited to join the Zeiss company based on his invention. A century after its first publication, a translation of Köhler's original article, "A New System of Illumination for Photomicrographic Purposes", was reprinted in the "Köhler Illumination Centenary" commemorative issue by the Royal Microscopical Society in 1994. [http://micro.magnet.fsu.edu/optics/timeline/people/kohler.html Pioneers in optics: August Köhler] ] Today, the Köhler illumination is considered one of the most important principles in achieving the best optical resolution on a light microscope.

Other contributions to microscope development

When Köhler joined Zeiss in 1900, Ernst Abbe and glass specialist Otto Schott had already paved the way for microscope improvements through their contributions to precise optical theory and the development of appropriate glass formulas. Köhler's expertise and his illumination technique helped to improve the microscope optics to achieve optimum resolution, using the entire resolving power of Abbe's objectives.

Köhler remained an active staff member of Zeiss for 45 years, contributing numerous innovations during this time. These include the development of a microscope operating with ultraviolet light (together with his colleague Moritz von Rohr), pioneering what would become the starting point for fluorescence microscopy [ [http://www.mti.uni-jena.de/~i6koka/history/start.html History of optics in Jena] ] , and the discovery of grid illumination, a method that would later be used in the treatment of tumors. A suggestion by Köhler led to the development of parfocal lenses which allow the specimen to remain in focus when changing objectives on a microscope.

Patents and publications

As a member of Zeiss, August Köhler filed at least 25 patent applications in Europe as well as at least ten patents in the USA. His patents include projection methods and illumination for kinematographs, microscope applications, and light and dark field illumination, among others. He filed an application for a fixed-ocular microscope of his design in Germany on April 16 1924 and with the United States Patent Office on March 31 1925 (patent number 1649068). [ [http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F1649068 USPTO patent image database] ] His publications include essays on microscopy and projection systems, and in particular his specialty of microphotography. His contributions to biology include fine structure analyses of diatoms.

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • August Köhler — ist der Name folgender Personen: August Köhler (Pädagoge) (1821–1879), deutscher Kindergartenpädagoge August Köhler (Theologe) (1835–1897), deutscher lutherischer Theologe August Köhler (Gouverneur) (1858–1902), deutscher Gouverneur von Togoland… …   Deutsch Wikipedia

  • August Köhler (Pädagoge) — Köhler August Köhler (* 9. September 1821 in Traßdorf; † 22. April 1879 in Gotha) war ein Gothaer Kindergartenpädagoge und Nachfolger von Friedrich Wilhelm August Fröbel. Inhaltsverzeichnis …   Deutsch Wikipedia

  • August Köhler (Gouverneur) — August Walter Köhler (* 30. September 1858 in Weilburg; † 20. Januar 1902 in Lomé) war ein deutscher Beamter im Reichskolonialamt und erster Gouverneur der deutschen Kolonie Togoland. Köhler begann seine Laufbahn in der Kolonialverwaltung 1891… …   Deutsch Wikipedia

  • August Köhler (Optiker) — August Karl Johann Valentin Köhler (* 4. März 1866 in Darmstadt; † 12. März 1948 in Jena) war ein deutscher Professor und Mitarbeiter bei Zeiss in Jena. Er ist vor allem für die Entwicklung der Köhler Beleuchtung in der Mikroskopie bekannt, die… …   Deutsch Wikipedia

  • Köhler (Familienname) — Köhler bzw. Koehler ist ein deutschsprachiger Familienname. Herkunft und Bedeutung Der Familienname Köhler geht auf den Beruf des Köhlers zurück. Bekannte Namensträger Inhaltsverzeichnis A B C D E F G H I J K L M …   Deutsch Wikipedia

  • Köhler illumination — is a type of specimen illumination used in transmitted or reflected light microscopy [ [http://www.olympusmicro.com/primer/anatomy/kohler.html Olympus Microscopy Resource Center Köhler Illumination] ] . It was designed by August Köhler in 1893,… …   Wikipedia

  • Köhler — is a German surname and may refer to:*August Köhler, microscopist and inventor of the Köhler illumination *Benjamin Köhler, football player *Ernesto Köhler, flute player and composer *Eva Köhler, First Lady of Germany *Georges J. F. Köhler,… …   Wikipedia

  • Köhler — puede hacer referencia a: August Köhler, microscopista alemán. Benjamin Köhler, futbolista alemán. Ernesto Köhler, flautista y compositor alemán. Eva Köhler, primera dama alemana. Georges J. F. Köhler, biólogo y nobel de medicina alemán. Gundolf… …   Wikipedia Español

  • Köhler —  Cette page d’homonymie répertorie des personnes (réelles ou fictives) partageant un même patronyme.  Pour les articles homophones, voir Kohler, Koehler et Koller. August Köhler (1866 1948), scientifique allemand spécialisée en… …   Wikipédia en Français

  • Kohler Mira Ltd — Industry Plumbing Predecessor Walker Crosweller Co Ltd (1921 1986) Caradon Mira Ltd (1986 2001) Founded 2001 Headquarters Cromwell Road, Cheltenham, Gloucestershire GL52 5EP Products Bathro …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”