Schmidt, Bernhard Voldemar

[shmit] (1879–1935) Estonian–German optical engineer: designer of a novel telescope system.

As a young man, Schmidt had several dull jobs before he took a course in engineering and set up his own workshop to build telescopes. He ground and polished the mirrors unaided, despite having lost his right arm in an accident with explosives. From 1926 he worked with the Hamburg Observatory staff; he was an alcoholic and died in a mental hospital.

Before his work, large telescopes gave good images only in the centre of the field; further from the optical axis the images of stars showed a tail (coma), which made making star maps difficult. Schmidt designed in 1930 a reflecting telescope with a spherical mirror, and with a smaller glass corrector plate in front, at the centre of curvature. The specially shaped aspherical plate provides the telescope with good definition over a wide field at low power. The telescope is usually used as a camera, and it revolutionized optical astronomy. From this design other catadioptric systems were developed, such as the Maksutov, which has a spherical meniscus corrector plate; it is compact and, like the Schmidt camera, combines useful features of reflecting and refracting telescopes.