Joseph Fraunhofer

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Date: Oct. 1, 2014
Publisher: Gale
Document Type: Biography
Length: 532 words
Content Level: (Level 4)
Lexile Measure: 1240L

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About this Person
Born: March 06, 1787 in Straubing, Germany
Died: June 07, 1826 in Munich, Germany
Nationality: German
Occupation: Optician
Updated:Oct. 1, 2014
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From humble beginnings as the son of a poor glass grinder, Joseph von Fraunhofer pursued a successful business career in optics and, in the process, made important contributions to physics and the theory of light through his study of the dark lines in the solar spectrum. Fraunhofer was born in Straubing, Bavaria (now Germany). At the age of 12, after experiencing the death of both of his parents, Fraunhofer became an apprentice to a lens and mirror maker. Fraunhofer received little formal education during his childhood, and he possibly would have remained a glassmaker if not for an accident that nearly took his life.

In 1801, the house in which Fraunhofer worked collapsed. Buried but virtually unharmed, Fraunhofer came to the notice of Joseph Utzschneider, an entrepreneur, and Maximilian Joseph, who would later became King Maximilian I of Bavaria. Both men offered Fraunhofer financial and fatherly support. Scholars suggest Utzschneider gave Fraunhofer books and an informal education in the field of optics and physics. Through Utzschneider's influence, Fraunhofer became an assistant in 1806 at a mathematical and technical institute started by Utzschneider and his associates. Fraunhofer then became a partner and manager in Utzschneider's optical institute at Benediktbeuern near Munich. In 1814, Fraunhofer and Utzschneider formed a new optical firm together.

Fraunhofer initiated the field of spectrum analysis with his study of optics, along with his interest in designing achromatic objective lenses for telescopes. During his work, he found numerous dark lines in a solar light spectrum. English chemist and physicist William H. Wollaston (1766-1828) had noticed several of these lines earlier in 1802, but paid them little attention. Fraunhofer, however, was interested in the spectral lines because they could be used as wavelength standards to determine the index of refraction of optical glasses. Fraunhofer accurately plotted hundreds of the spectral lines. By measuring the wavelength of more than 300 of the lines he saw in his solar spectrum, Fraunhofer discovered that the lines' relative positions in the spectra of elements are constant. Fraunhofer assigned the most prominent lines with letters from A to Z, a nomenclature still in use today. Other physicists, however, quickly recognized that the Fraunhofer lines, as they became known, could help discover properties of the solar atmosphere. Building on Fraunhofer's discovery, Prussian-born physicist Gustav Kirchhoff and others developed the science of spectroscopy, which revolutionized solar physics. In fact, most data obtained about the Sun and stars is still obtained through spectroscopy. Fraunhofer also built the first diffraction grating, which he used to measure wavelengths of specific colors and dark lines in the solar spectrum. Fraunhofer did not taint his work with deductive interpretations. Rather, he confined himself to scientific empirical observations. The optical instruments he developed allowed him to conduct fundamental research in the fields of light and optics.

A master craftsman who was also successful as an inventor, entrepreneur, and researcher, Fraunhofer was awarded an honorary doctorate degree from the University of Erlangen in 1822. He was appointed director of the Physics Museum in Munich and taught at the University of Bavaria. He was made a Knight of the Danish order of Danebrog in 1824. Fraunhofer died two years later at age 39 from tuberculosis.

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Gale Document Number: GALE|K2434100079