Karl Strehl

Karl Wilhelm Andreas Strehl (born April 30, 1864 in Bayreuth ; † June 14, 1940 in Hof ) was a German physicist and optician.

In his main work Theory of the Telescope on the Basis of Diffraction of Light , he described the relationships and the meaning of the brightness in the first diffraction ring and formulated a method for calculating the definition brightness. The definition brightness describes the ratio of the theoretically maximum possible intensity of the central diffraction disk of a perfect optic to the intensity of the central diffraction disk of a real existing optic when imaging a point-like object. According to Karl Strehl, the definition brightness is called the Strehl number or Strehl ratio today.

Life

Karl Wilhelm Andreas Strehl was born on April 30, 1864 in Bayreuth. There he attended grammar school from 1874 to 1882. From 1883 to 1887 he studied physics and mathematics in Erlangen and Munich. He completed his studies on October 28, 1887 with the main examination of teaching qualifications in mathematics and physics. After graduating, he got his first job as an assessor on October 1, 1889 at the Augsburg Business School. From October 27, 1890, he moved to the grammar school in Landau id Pfalz, where he worked until 1894. From September 1, 1894 he became a high school teacher in Weißenburg, where he worked until 1897. In Weißenburg he married the kindergarten teacher Barbara Anna Reisinger on December 28, 1894. From November 16, 1897 to 1905, he then worked as a high school teacher in Erlangen. In Erlangen he obtained his doctorate (Dr. phil.) On February 20, 1900. Then on October 1, 1905, he switched to the Jean-Paul-Gymnasium in Hof, where he worked as a grammar school teacher and finally senior teacher until his retirement on September 1, 1923. During the war he was awarded the Prussian Cross of Merit on July 24, 1918.

Web links

• Karl Strehl - Franconian scholar, physicist and optician of world renown by Kurt Hopf
• List of publications by Karl Strehl by Kurt Hopf

Works

• Strehl, K. 1895, Aplanatic and incorrect image in the telescope , Zeitschrift für Instrumentenkunde 15 (Oct.), 362–370.
• Strehl, K. 1902, On air streaks and zone defects , Zeitschrift für Instrumentenkunde , 22 (July), 213–217. [PDF file]