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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
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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
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212:, 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.
319:. 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.
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on 31 March 1925 (patent number 1649068). 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
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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
456:, 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 16 April 1924, and with the
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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
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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
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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
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in 1994. Today, the Köhler illumination is considered one of the most important principles in achieving the best optical resolution on a light microscope.
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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
224:, Germany, where he attended the Ludwig-Georgs-Gymnasium until 1884. He studied at the Technical University in Darmstadt and at the universities of
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276:, a project that depended heavily on microscopic imaging and prompted Köhler into trying to improve the quality of images taken via
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and condenser focus control. This superior illumination scheme is still widely used in modern microscopes and forms the basis for
332:, mirrors or other primitive light sources, resulting in an uneven specimen illumination unsuited for producing good quality
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in 1893, Köhler worked a number of years as a grammar school teacher in Bingen. In 1900, he was invited to join the
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company based on his invention. A century after its first publication, a translation of Köhler's original article,
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one year later. Its significance was not noted until several years later when Köhler was invited to join the
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lenses which allow the specimen to remain in focus when changing objectives on a microscope.
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based on his earlier work on improving microscope illumination. He stayed with Zeiss as a
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In 1888, August Köhler graduated with a teaching degree and subsequently taught at
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349:. This in turn allowed the condenser to be focused on the specimen using a field
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196:(4 March 1866 – 12 March 1948) was a German professor and early staff member of
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Köhler's groundbreaking work on microscope illumination was published in the
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Zeitschrift für wissenschaftliche
Mikroskopie und für Mikroskopische Technik
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272:, Germany. The object of his doctorate thesis was the taxonomy of
564:"Ein neues Beleuchtungsverfahren für mikrophotographische Zwecke"
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587:"New Method of Illimination for Phomicrographical Purposes"
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436:, a method that would later be used in the treatment of
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Fundamentals of light microscopy and electronic imaging
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280:. The result of this work was published in 1893.
502:Zeitschrift für wissenschaftliche Mikroskopie
404:Other contributions to microscope development
375:Zeitschrift für wissenschaftliche Mikroskopie
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591:Journal of the Royal Microscopical Society
381:Journal of the Royal Microscopical Society
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417:resolving power of Abbe's objectives.
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232:covering a wide range of fields from
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408:When Köhler joined Zeiss in 1900,
359:differential interference contrast
194:August Karl Johann Valentin Köhler
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611:Pioneers in optics: August Köhler
545:, Wiley-Liss, Inc., New York,
125:honorary doctor degree of the
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683:Businesspeople from Darmstadt
424:(together with his colleague
394:Köhler Illumination Centenary
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256:Teaching and academic career
16:German scientist (1886–1948)
640:USPTO patent image database
627:September 30, 2007, at the
458:United States Patent Office
398:Royal Microscopical Society
396:commemorative issue by the
220:Köhler was born in 1866 in
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541:Douglas B. Murphy (2001):
622:History of optics in Jena
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673:Engineers from Darmstadt
585:Koehler, August (1894).
448:Patents and publications
216:Early life and education
98:University of Heidelberg
562:Köhler, August (1893).
432:, and the discovery of
430:fluorescence microscopy
392:, was reprinted in the
182:Johann Wilhelm Spengel
412:and glass specialist
341:focused on the front
336:using the slow-speed
289:University of Giessen
157:University of Giessen
103:University of Giessen
678:Carl Zeiss AG people
283:After receiving his
65:Grand Duchy of Hesse
517:Naturwissenschaften
367:confocal microscopy
323:Köhler illumination
293:Zeiss Optical Works
210:Köhler illumination
167:Zeiss Optical Works
116:Köhler illumination
529:10.1007/BF01476460
317:University of Jena
162:University of Jena
127:University of Jena
434:grid illumination
422:ultraviolet light
301:Siegfried Czapski
264:in Darmstadt and
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134:Scientific career
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77:(1948-03-12)
57:4 March 1866
663:1948 deaths
658:1866 births
414:Otto Schott
295:company in
40: 1930
652:Categories
597:: 261–262.
469:References
410:Ernst Abbe
262:gymnasiums
242:mineralogy
226:Heidelberg
206:microscopy
53:1866-03-04
351:diaphragm
347:condenser
338:emulsions
330:gas lamps
309:professor
305:physicist
287:from the
250:chemistry
222:Darmstadt
144:Physicist
85:, Germany
61:Darmstadt
625:Archived
442:parfocal
343:aperture
463:diatoms
345:of the
315:at the
274:limpets
270:Giessen
246:physics
234:zoology
230:Giessen
35:Köhler
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438:tumors
365:, and
266:Bingen
248:, and
238:botany
140:Fields
122:Awards
547:ISBN
311:for
297:Jena
236:and
228:and
202:Jena
83:Jena
72:Died
47:Born
525:doi
240:to
200:in
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477:^
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51:(
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