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Karl Strehl
Karl Wilhelm Andreas Strehl (April 30, 1864 – June 14, 1940) was a German physicist, author and mathematician. He is notable for the Strehl ratio, a widely used measurement for the optical quality of an imaging system.Strehl, K. 1902, ''Über Luftschlieren und Zonenfehler'', Zeitschrift für Instrumentenkunde, 22 (July), 213–217[PDF file]/ref> See also * Strehl ratio References 1864 births 1940 deaths 20th-century German physicists German male writers 19th-century German mathematicians 20th-century German mathematicians 19th-century German physicists {{Germany-physicist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of natural phenomena and the development and analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies (also known as applie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strehl Ratio
The Strehl ratio is a measure of the quality of optical image formation, originally proposed by Karl Strehl, after whom the term is named. Used variously in situations where optical resolution is compromised due to lens aberrations or due to imaging through the turbulent atmosphere, the Strehl ratio has a value between 0 and 1, with a hypothetical, perfectly unaberrated optical system having a Strehl ratio of 1. Mathematical definition The Strehl ratio S is frequently defined as the ratio of the peak aberrated image intensity from a point source compared to the maximum attainable intensity using an ideal optical system limited only by diffraction over the system's aperture. It is also often expressed in terms not of the peak intensity but the intensity at the image center (intersection of the optical axis with the focal plane) due to an on-axis source; in most important cases these definitions result in a very similar figure (or identical figure, when the point of peak intensity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1864 Births
Events January–March * January 13 – American songwriter Stephen Foster ("Oh! Susanna", "Old Folks at Home") dies aged 37 in New York City, leaving a scrap of paper reading "Dear friends and gentle hearts". His parlor song " Beautiful Dreamer" is published in March. * January 16 – Denmark rejects an Austrian-Prussian ultimatum to repeal the Danish Constitution, which says that Schleswig-Holstein is part of Denmark. * January 21 – New Zealand Wars: The Tauranga campaign begins. * February – John Wisden publishes '' The Cricketer's Almanack for the year 1864'' in England; it will go on to become the major annual cricket reference publication. * February 1 – Danish-Prussian War (Second Schleswig War): 57,000 Austrian and Prussian troops cross the Eider River into Denmark. * February 15 – Heineken brewery founded in Netherlands. * February 17 – American Civil War: The tiny Confederate hand-propelled submarine ''H. L. Hunl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1940 Deaths
Year 194 ( CXCIV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Septimius and Septimius (or, less frequently, year 947 ''Ab urbe condita''). The denomination 194 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Emperor Septimius Severus and Decimus Clodius Septimius Albinus Caesar become Roman Consuls. * Battle of Issus: Septimius Severus marches with his army (12 legions) to Cilicia, and defeats Pescennius Niger, Roman governor of Syria. Pescennius retreats to Antioch, and is executed by Severus' troops. * Septimius Severus besieges Byzantium (194–196); the city walls suffer extensive damage. Asia * Battle of Yan Province: Warlords Cao Cao and Lü Bu fight for control over Yan Province; the battle lasts for over 100 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Male Writers
German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Germanic peoples (Roman times) * German language **any of the Germanic languages * German cuisine, traditional foods of Germany People * German (given name) * German (surname) * Germán, a Spanish name Places * German (parish), Isle of Man * German, Albania, or Gërmej * German, Bulgaria * German, Iran * German, North Macedonia * German, New York, U.S. * Agios Germanos, Greece Other uses * German (mythology), a South Slavic mythological being * Germans (band), a Canadian rock band * "German" (song), a 2019 song by No Money Enterprise * ''The German'', a 2008 short film * "The Germans", an episode of ''Fawlty Towers'' * ''The German'', a nickname for Congolese rebel André Kisase Ngandu See also * Germanic (other) * Germa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
19th-century German Mathematicians
The 19th (nineteenth) century began on 1 January 1801 ( MDCCCI), and ended on 31 December 1900 ( MCM). The 19th century was the ninth century of the 2nd millennium. The 19th century was characterized by vast social upheaval. Slavery was abolished in much of Europe and the Americas. The First Industrial Revolution, though it began in the late 18th century, expanding beyond its British homeland for the first time during this century, particularly remaking the economies and societies of the Low Countries, the Rhineland, Northern Italy, and the Northeastern United States. A few decades later, the Second Industrial Revolution led to ever more massive urbanization and much higher levels of productivity, profit, and prosperity, a pattern that continued into the 20th century. The Islamic gunpowder empires fell into decline and European imperialism brought much of South Asia, Southeast Asia, and almost all of Africa under colonial rule. It was also marked by the collapse of the large S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
