Bernhard Schmidt (optician)

Bernhard Schmidt

Bernhard Schmidt (* March 30th ^July / April 11th  1879 ^greg. On the island Naissaar (German Nargen ) belonging to Estonia ; †  December 1st 1935 in Hamburg ) was an optician specializing in astronomical optics . The Schmidt telescope , which is also known as the Schmidt camera or Schmidt mirror , is named after him .

life and work

As a teenager, Bernhard Schmidt lost his right hand while playing with gunpowder . Despite this handicap, he not only shone with his theoretical knowledge, but above all with the production of perfect lenses and mirrors .

Bernhard Schmidt studied electrical engineering at the Technikum Mittweida from 1901 to 1904, and from 1903 he manufactured hand-cut mirrors and lenses with the highest precision in his workshop in Mittweida . In addition to the production of various large mirrors and lenses for astronomical devices, he improved existing optics through retouching . This is how he came into contact with the observatory in Hamburg-Bergedorf , where he had been working as a freelancer since 1926.

In Hamburg he succeeded in inventing a completely new type of mirror telescope , which is now known as the Schmidt mirror , Schmidt telescope or Schmidt camera . The Schmidt camera soon found widespread use in astrophotography because of its large image angle and the highest image quality right into the corners of the photo plates . The success of the Schmidt telescope was also possible because Schmidt decided not to apply for a patent for his great idea.

For the mirror telescopes named after him, Schmidt used a combination of a spherical mirror and a thin refractive correction plate ( Schmidt plate ) placed in front of it in its center plane . This avoids the disadvantages of large imaging parabolic mirrors (small image field, difficult production) and large refractors ("sagging" of the large, heavy lenses, secondary spectrum).

To manufacture the correction plate, which is extremely difficult to manufacture, Schmidt developed and practiced his own manufacturing process: a plane-parallel glass plate is deliberately deformed with negative pressure . In this state, the plate is ground flat or spherical again and polished. After polishing, the plate is relaxed. The deviation of a few tens of micrometers of such a plate from plane parallelism is sufficient to eliminate the spherical aberration and coma of a spherical mirror and thus to use its large image field without imaging errors. Since the deformation of the plate due to its own weight only indirectly affects the image quality, it was now possible for the first time to create high-light telescopes with a large numerical aperture or a large opening angle.

Honors

Bernhard Schmidt is the main character in the 1987 novel Vastutuulelaev (in German about ship in the headwind ) by the Estonian writer Jaan Kross (1920–2007).

The asteroid (1743) Schmidt and (together with two namesakes) the moon crater Schmidt is named after Schmidt . The Schmidtweg in the Hamburg district of Bergedorf and the Bernhard Schmidt primary school in Mittweida are also named after Bernhard Schmidt.

Works

The Alfred Jensch telescope, the world's largest Schmidt camera

• A bright, coma-free mirror system. In: Centralzeitung für Optik und Mechanik , Volume 52, 1931, pp. 25-26 and Mitteilungen der Hamburger Sternwarte in Bergedorf , Volume 7, No. 36, 1932, pp. 15-17, available online

literature

• Richard Schorr: Bernhard Schmidt. Astronomical News No. 6171, January 1936 Vol. 528
• Arthur Arno Wachmann: The life of the optician Bernhard Schmidt. in: Stars and Space 1962/2, pp. 28–32
• Rolf Riekher: Telescopes and their masters. 2nd Edition. Verlag Technik, Berlin 1990, pp. 321–326, ISBN 3-341-00791-1
• Siegfried Marx, Werner Pfau: Sky photography with Schmidt telescopes. Urania-Verlag, Leipzig 1990, 167 pp., 97 ills., ISBN 3-332-00214-7
• Erik Schmidt : Optical Illusions: The Life Story of Bernhard Schmidt, the Great Stellar Optician of the Twentieth Century . Teaduste Akadeemia Kirjastus, 1995, ISBN 9985-50-102-0 .
• Erik Schmidt: Minu Onu Bernhard Schmidt . Ilmamaa, 2002, ISBN 9985-77-061-7 .
• Barbara Dufner: The sky firmly in view, a scientific biography about the astro-optician Bernhard Schmidt. Franz Steiner Verlag, Stuttgart 2002, 337 pages, ISBN 3-515-08097-X .
• Erik Schmidt: Bernhard Schmidt 1879-1935 . 2004.
• Barbara Dufner:  Schmidt, Bernhard Woldemar. In: New German Biography (NDB). Volume 23, Duncker & Humblot, Berlin 2007, ISBN 978-3-428-11204-3 , p. 179 f. ( Digitized version ).
• J. Schramm: Stars over Hamburg - The history of astronomy in Hamburg . 2nd revised and expanded edition, Kultur- & Geschichtkontor, Hamburg 2010, ISBN 978-3-9811271-8-8
• Jan-Peter Domschke, Sabine Dorn, Hansgeorg Hofmann, Rosemarie Poch, Marion Stascheit: Mittweida's engineers all over the world . Hochschule Mittweida (Ed.): Mittweida 2014, p. 98f.

Web links

• Literature by and about Bernhard Schmidt in the catalog of the German National Library
• Schmidt Museum of the Hamburg observatory
• Private page depicting Schmidt's work