SCHMIDT, BERNHARD VOLDEMAR

(b. Naissaar, Estonia [now Estonia S.S.R.], 30 March 1879; d. Hamburg, Germany, 1 December 1935)

optics.

Schmidt studied in Göteborg, Sweden, and then engineering in Mittweida, Saxony, where he established a small workshop for the manufacture of astronomical mirrors (up to about twenty centimeters in diameter). Their perfection was much appreciated. In 1905 Schmidt constructed for the Potsdam Astrophysical Observatory the first reflector with an aperture of forty centimeters and with a focal length of about one meter. Schmidt-already had used for Cassegrain reflectors a spherical mirror that corrected spherical aberration by an adequate deformation of the second mirror.

In addition to the construction of astronomical instruments. Schmidt also improved and himself used some of the great objectives (for example, at the Hamburg observatory, Bergedorf). In 1909 he constructed for his own small observatory at Mittweida a new horizontal reflector, later on named “Uranostat,” which consisted of a parabolic mirror of forty-centimeter aperture and of eleven-meter focal length. The reflector was mounted so that the axis was in the north-sourth direction and caught the light of the object to be observed from two plane mirrors rotatable around two perpendicular axes.

Later Schmidt constructed two similar arrangements of several mirrors for the Bergedorf and Breslau observatories. In 1926 Schmidt moved to Bergedorf. where with the first arrangement he himself made excellent photographs of Jupiter, Saturn, and the moon.

Schmidt always was an odd man, who neither married nor was willing to lead a normal life. He once said that he got his best ideas on awaking slowly after some days of complete intoxication. Drink was certainly the cause of his early death. At the Bergedorf observatory he had no regular duties and was free of economic worries, receiving generous aid from R. Schorr, the director of the observatory. Schmidt thus had the time and the resources to carry out his most famous work-the construction of a reflector without coma. He used a correction plate shaped as a very small curved circular torus, which compensates for spherical aberration and coma. Photographs could now be taken which yielded undistorted star images over a large field: formerly only objects near the optical axis could be delineated.

Schmidt had lost his right arm in an accident in his youth, but he nevertheless did all of his work alone and unaided. He polished his mirrors by hand, using glass instead of metal disks.

Schmidt spent the last year of his life in a mental hospital and died there.

BIBLIOGRAPHY

Schmidt’s only work is “Ein lichtstarkes komafreies Spiegelsystem,” in Zentralzeitung für Optik und Mechanik, Elektrotechnik, 52 (1931), 25–26, For works on Schmidt and his work, see B. Strömgren, “Das Schmidt’sche Spiegelteleskop,” in Vierteljahrsschrift der Astronomischen Gesellschaft, 70 (1935), 65–86; and A. A. Wachmann, “From the Life of Bernhard Schmidt,” in Sky and Telescope, 15 (1959), 4–9.

H.-Christ. Freiesleben