A Brief HISTORY of Thin-Film Optics in Jena

Goethe’s Theory of Colors

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Goethe’s Color Circle

My home town of Jena, Germany, is a renowned place for optics and also for thin-film optics, my field of work. The beginning of optics in Jena was marked by Johann Wolfgang von Goethe (1749-1832) in the early 19th century. Goethe came to Jena, 20 kilometers from Weimar, to check on the development of the botanical garden that he had founded in Jena or to sometimes meet his poet colleague, Frederic Schiller (1759-1812). Within his numerous natural scientific studies, Goethe had dealt with optics, and particularly with colors. He developed his own color theory, which has only historical value as seen from today’s point of view, but which attracted great interest and publicity at Goethe’s time due to his reputation. Citation from Goethe’s “Theory of Colours, Part VI – Effect of Colour with Respect to Moral Associations, §759”:

“People experience a great delight in color, generally. The eye requires it as much as it requires light. We have only to remember refreshing sensations we experience, such as if on a cloudy day the sun illuminates a single portion of the scene before us and displays its colours. The healing powers were ascribed to coloured gems, (which) may have arisen from the experience of this indefinable pleasure.”

 


Carl Zeiss

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Carl Zeiss 1860

During his studies and experiments in optics and about the theory of colors, Goethe was supported by the “Mechanic to the Court” of the University of Jena, Fredric Willem Koerner (1778-1847). In the 1830s, Koerner had an apprentice named Carl Zeiss (1816-1888) from Weimar who learnt not only the craft of mechanics but also (and urged, among others, Goethe’s theory of colors) acquired mathematical and natural science knowledge by attending lectures at the University of Jena. Right about this time, Matthias Jacob Schleiden (1804-1881) taught at the University. Schleiden, as a famous botanist and co-founder of the theory of cells, inspired Koerner and finally the young Zeiss to make microscopes and, if possible, better ones than were available at that time.

Carl Zeiss founded a small optical factory in 1846 in the city of Jena, and introduced his first microscope on the market in 1847. This microscope was indeed better than the competitor’s and it became a bestseller because it was nevertheless cheaper. The business grew quickly and it continued to improve when Zeiss built the first transportable microscope composed of prefabricated parts that could be broken down and pieced together. So, as with his teacher Koerner, Zeiss also received the title “Mechanic to the Court” in 1860.

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Ernst Abbe and Otto Schott

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Otto Schott about 1890

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Ernst Abbe about 1875

Beginning in 1863, the young physicist Ernst Abbe (1840-1905) taught as an assistant professor at the University of Jena. He became Zeiss’s business partner and originated the scientific basics of optics as the essential foundation of Zeiss’s company. Zeiss and Abbe started their direct cooperation in 1866 and in 1875, Abbe became a co-owner of Zeiss’s company. When they developed novel optics for telescopes and microscopes, the quality of glass used for lenses became a looming problem. Consequentially, they invited a third partner to join them, Otto Schott (1851-1835), who developed the truly novel aspect of their optics, the glass. In 1884, the Otto Schott Glass-Technical Laboratory was founded, providing the significantly growing optical industry, established in Jena, with the required high-quality glass.
 


Ernst Abbe and the Carl-Zeiss-Foundation

Volkshaus in Jena um 1903

‘Volkshaus’ in Jena about 1903

Ernst Abbe was not only a scientist but also an entrepreneur and social reformer, who was far ahead of his time with his ideas. In 1889, he founded the Carl-Zeiss-Foundation and made it the sole owner of the Zeiss Company and the co-owner of the SCHOTT Company. The fundamental idea of Abbe in this approach was the intention to secure both companies’ independence of any personal interests of their former owners. The development of the company showed that an industrial enterprise could indeed be attractive and act responsibly (with its employees) under the existing social conditions, a concept which was unique at this time and worldwide. When Abbe met Zeiss for the first time in 1863, Zeiss had only 25 employees and had a sales volume of 12,618 marks. In Abbe’s year of death in 1905, the Zeiss Company employed 1400 employees and had a sales volume of more than 5 million marks. From this early time, the city of Jena and the University of Jena have benefited from the foundation’s capital donations provided by this enterprise’s profits.

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Zeiss Jena and the Beginning of Thin-Film Optics in Jena

Filter von Geffcken

Geffcken’s paper on filters

Generally speaking, thin-film optics as an important part of the optics industry started in Jena in 1935. At this time, “T-coating” was applied for the antireflection of lenses for the very first time. With T-coating, a thin film was deposited on lenses through evaporation under a high vacuum (German Patent 685767, filed Nov. 1, 1935). This coating eliminates the parasitic reflexes at a glass/air boundary by interference and results in more contrast, but with more light within the optics. The inventor was the head of the crystal laboratory at Zeiss Jena, Alexander Smakula, PhD (1900-1983).

At the Schott Company in Jena, another physicist, Walter Geffcken (1904-1995) experimented with thin films, which were deposited by a solution. He also worked out the first theoretical design for an anti-reflective coating on lenses involving more than one thin film (German Patent 758767, filed July 7, 1940). Geffcken was also the inventor of the first interference filters to select very narrow spectral ranges from the white light spectrum using a combination of dielectric and metallic films (German Patent 716153, filed Dec. 1, 1939), which later became an essential component of thin-film optics.
 


The Coating Laboratory in Jena

After World War II, the Zeiss factory was shared: The US Army had occupied Thuringia, Germany in April 1945, but they left again in July 1945 and turned the “Free State” of Thuringia over to the Soviets as part of an earlier agreement. With the Americans, numerous “Heads and Patents” went immediately along to the United States. A lot of ”Zeissians“ left the Soviet Occupation Zone that formed at this time and founded a new Zeiss factory in the western part of Germany, in Oberkochen; a new Schott factory was also finally established in Mainz. The Soviets also deported to Russia a lot of executives, exported still more machines and even entire parts of factories. The Zeissians who remained in Jena started to rebuild Zeiss with the ruins that remained and with the ideas and plans they still had in their heads.

Uwe Schallenberg 1977

Uwe Schallenberg 1977

In 1948, a coating laboratory was again established in Zeiss Jena. The physicist Hubert Pohlack (1918-2012) became the first scientific assistant at the laboratory. He made a significant contribution to the theory of thin-film optics in his paper “Die Synthese optischer Interferenzschichten mit vorgegebenen Spektraleigenschaften“, published in 1952 and he became the head of the laboratory in 1954. The young physicist Herbert Koch became a scientific assistant in the thin-film laboratory in 1955 and in 1964 he was named the head of the laboratory. In 1965, his paper “Optische Untersuchungen zur Wasserdampfsorbtion in Aufdampfschichten” was published and it is still often cited today.

Finally, in March 1977, directly after finishing my degree in physics at the University of Jena, I started my career as a scientific assistant in this thin-film laboratory.

Thin-film optics and light are my passions.


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