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Joseph von Fraunhofer

Joseph von Fraunhofer (March 6, 1787 – June 7, 1826) was a German optician. When Fraunhofer became an orphan at the age of 11, he started working as an apprentice to a harsh glassmaker named Philipp Anton Weichelsberger.

Biography

In 1801 the workshop in which he was working collapsed and he was buried in the rubble. The rescue operation was led by Maximilian IV Joseph, Prince Elector of Bavaria (the future Maximilian I Joseph). The prince entered Fraunhofer's life, providing him with books and forcing his employer to allow the young Joseph Fraunhofer time to study.

After eight months of study, Fraunhofer went to work at the Optical Institute at Benediktbeuern, a secularised Benedictine monastery devoted to glass-making. There he discovered how to make the world's finest optical glass and invented incredibly precise methods for measuring dispersion. In 1818 he became the director of the Optical Institute. Due to the fine optical instruments he had developed, Bavaria overtook England as the centre of the optics industry. Even the likes of Michael Faraday were unable to produce glass that could rival Fraunhofer's.

His illustrious career eventually earned him an honorary doctorate from the University of Erlangen in 1822. In 1824, he was awarded the order of merit, became a noble, and made an honorary citizen of Munich. Like many glassmakers of his era who were poisoned by heavy metal vapors, Fraunhofer died young, in 1826 at the age of 39. His most valuable glassmaking recipes are thought to have gone to the grave with him.

Scientific research

In 1814, Fraunhofer invented the spectroscope, and discovered 574 dark lines appearing in the solar spectrum. These were later shown to be atomic absorption lines, as explained by Kirchhoff and Bunsen in 1859. These lines are still sometimes called Fraunhofer lines in his honour.

He also invented the diffraction grating and in doing so transformed spectroscopy from a qualitative art to a quantitative science by demonstrating how one could measure the wavelength of light accurately. He found out that the spectra of Sirius and other first-magnitude stars differed from each other and from the sun, thus founding stellar spectroscopy.

Ultimately, however, his primary passion was still practical optics, once noting that "In all my experiments I could, owing to lack of time, pay attention to only those matter which appeared to have a bearing upon practical optics."

Fraunhofer lines

File:High Resolution Solar Spectrum-2.jpg

Solar Fraunhofer lines.

The Fraunhofer lines are a set of spectral lines named after Fraunhofer. The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun.

In 1802, English chemist William Hyde Wollaston was the first person to note the appearance of a number of dark features in the solar spectrum. In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the wavelength of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters.

It was later discovered by Gustav Kirchhoff and Robert Bunsen that each chemical element was associated with a set of spectral lines, and deduced that the dark lines in the solar spectrum were caused by absorption by those elements in the upper layers of the sun. Some of the observed features are also caused by absorption in oxygen molecules in the Earth's atmosphere.

The major Fraunhofer lines, and the elements they are associated with, are shown in the following table:

Designation	Element	Wavelength (nm)	Designation	Element	Wavelength (nm)
y	O₂	898.765	c	Fe	495.761
Z	O₂	822.696	F	H β	486.134
A	O₂	759.370	d	Fe	466.814
B	O₂	686.719	e	Fe	438.355
C	H α	656.281	G'	H γ	434.047
a	O₂	627.661	G	Fe	430.790
D₁	Na	589.592	G	Ca	430.774
D₂	Na	588.995	h	H δ	410.175
D₃ (or d)	He	587.5618	H	Ca⁺	396.847
e	Hg	546.073	K	Ca⁺	393.368
E₂	Fe	527.039	L	Fe	382.044
b₁	Mg	518.362	N	Fe	358.121
b₂	Mg	517.270	P	Ti⁺	336.112
b₃	Fe	516.891	T	Fe	302.108
b₄	Fe	516.751	t	Ni	299.444
b₄	Mg	516.733

Given their well-defined wavelengths, Fraunhofer lines are often used to characterize the refractive index and dispersion properties of optical materials.^[1]

Notes

↑ The Fraunhofer C-, F-, G'-, and h- lines correspond to the alpha, beta, gamma and delta lines of the Balmer series of emission lines of the hydrogen atom. The D₁ and D₂ lines form the well-known "sodium doublet," the center wavelength of which (587.5618 nm) is given the designation letter "D." There is disagreement in the literature for some line designations; e.g., the Fraunhofer d-line may refer to the cyan iron line at 466.814 nm, or alternatively to the yellow helium line (also labeled D₃) at 587.5618 nm. Similarly, there is ambiguity with reference to the e-line, since it can refer to the spectral lines of both iron (Fe) and mercury (Hg). To resolve ambiguities that arise in usage, ambiguous Fraunhofer line designations are preceded by the element with which they are associated (e.g., Mercury e-line and Helium d-line).

References
ISBN links support NWE through referral fees

Aller, Lawrence H. (1991). Atoms, Stars and Nebulae, 3rd ed.. Cambridge University Press. ISBN 0-521-32512-9.

External links

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[1] The Fraunhofer C-, F-, G'-, and h- lines correspond to the alpha, beta, gamma and delta lines of the Balmer series of emission lines of the hydrogen atom. The D₁ and D₂ lines form the well-known "sodium doublet," the center wavelength of which (587.5618 nm) is given the designation letter "D." There is disagreement in the literature for some line designations; e.g., the Fraunhofer d-line may refer to the cyan iron line at 466.814 nm, or alternatively to the yellow helium line (also labeled D₃) at 587.5618 nm. Similarly, there is ambiguity with reference to the e-line, since it can refer to the spectral lines of both iron (Fe) and mercury (Hg). To resolve ambiguities that arise in usage, ambiguous Fraunhofer line designations are preceded by the element with which they are associated (e.g., Mercury e-line and Helium d-line).

[1]

@@ Line 1: / Line 1: @@
+{{Claimed}}
 [[Image:Fraunhofer 2.jpg|thumb|Joseph von Fraunhofer]]
-'''Joseph von Fraunhofer''' ([[March 6]], [[1787]] &ndash; [[June 7]], [[1826]]) was a [[Germany|German]] optician. When Fraunhofer became an [[orphan]] at the age of 11, he started working as an apprentice to a harsh glassmaker named Philipp Anton Weichelsberger.
+'''Joseph von Fraunhofer''' (March 6, 1787 &ndash; June 7, 1826) was a [[Germany|German]] optician. When Fraunhofer became an [[orphan]] at the age of 11, he started working as an apprentice to a harsh glassmaker named Philipp Anton Weichelsberger.
 ==Biography==
-In [[1801]] the workshop in which he was working collapsed and he was buried in the rubble. The rescue operation was led by Maximilian IV Joseph, [[prince-elector|Prince Elector]] of [[Bavaria]] (the future [[Maximilian I of Bavaria|Maximilian I Joseph]]). The prince entered Fraunhofer's life, providing him with books and forcing his employer to allow the young Joseph Fraunhofer time to study.
+In 1801 the workshop in which he was working collapsed and he was buried in the rubble. The rescue operation was led by Maximilian IV Joseph, [[prince-elector|Prince Elector]] of [[Bavaria]] (the future [[Maximilian I of Bavaria|Maximilian I Joseph]]). The prince entered Fraunhofer's life, providing him with books and forcing his employer to allow the young Joseph Fraunhofer time to study.
-After eight months of study, Fraunhofer went to work at the Optical Institute at [[Benediktbeuern Abbey|Benediktbeuern]], a secularised Benedictine monastery devoted to glass-making. There he discovered how to make the world's finest optical glass and invented incredibly precise methods for measuring dispersion. In [[1818]] he became the director of the Optical Institute. Due to the fine optical instruments he had developed, [[Bavaria]] overtook [[England]] as the centre of the optics industry. Even the likes of [[Michael Faraday]] were unable to produce glass that could rival Fraunhofer's.
+After eight months of study, Fraunhofer went to work at the Optical Institute at [[Benediktbeuern Abbey|Benediktbeuern]], a secularised Benedictine monastery devoted to glass-making. There he discovered how to make the world's finest optical glass and invented incredibly precise methods for measuring dispersion. In 1818 he became the director of the Optical Institute. Due to the fine optical instruments he had developed, [[Bavaria]] overtook [[England]] as the centre of the optics industry. Even the likes of [[Michael Faraday]] were unable to produce glass that could rival Fraunhofer's.
-His illustrious career eventually earned him an honorary doctorate from the [[University of Erlangen]] in [[1822]]. In [[1824]], he was awarded the order of merit, became a noble, and made an honorary citizen of [[Munich]]. Like many glassmakers of his era who were poisoned by [[heavy metals|heavy metal]] vapours, Fraunhofer died young, in [[1826]] at the age of 39. His most valuable glassmaking recipes are thought to have gone to the grave with him.
+His illustrious career eventually earned him an honorary doctorate from the [[University of Erlangen]] in 1822. In 1824, he was awarded the order of merit, became a noble, and made an honorary citizen of [[Munich]]. Like many glassmakers of his era who were poisoned by [[heavy metals|heavy metal]] vapors, Fraunhofer died young, in 1826 at the age of 39. His most valuable glassmaking recipes are thought to have gone to the grave with him.
 ==Scientific research==
-In [[1814]], Fraunhofer invented the spectroscope, and discovered 574 dark lines appearing in the solar spectrum.  These were later shown to be atomic absorption lines, as explained by [[Gustav Kirchhoff|Kirchhoff]] and [[Robert Bunsen|Bunsen]] in [[1859]].  These lines are still sometimes called ''[[Fraunhofer lines]]'' in his honour.
+In 1814, Fraunhofer invented the spectroscope, and discovered 574 dark lines appearing in the solar spectrum.  These were later shown to be atomic absorption lines, as explained by [[Gustav Kirchhoff|Kirchhoff]] and [[Robert Bunsen|Bunsen]] in 1859.  These lines are still sometimes called ''[[Fraunhofer lines]]'' in his honour.
 He also invented the [[diffraction grating]] and in doing so transformed [[spectroscopy]] from a qualitative art to a quantitative science by demonstrating how one could measure the wavelength of light accurately. He found out that the spectra of [[Sirius]] and other first-magnitude stars differed from each other and from the sun, thus founding stellar spectroscopy.
 Ultimately, however, his primary passion was still practical optics, once noting that "In all my experiments I could, owing to lack of time, pay attention to only those matter which appeared to have a bearing upon practical optics."
+== Fraunhofer lines ==
+[[Image:High Resolution Solar Spectrum-2.jpg|thumb|right|350px|Solar Fraunhofer lines.]]
+The '''Fraunhofer lines''' are a set of [[spectral line]]s named after Fraunhofer. The lines were originally observed as dark features ([[absorption line]]s) in the [[optical spectrum]] of the [[Sun]].
+In 1802, English chemist [[William Hyde Wollaston]] was the first person to note the appearance of a number of dark features in the solar spectrum. In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the [[wavelength]] of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters.
+It was later discovered by [[Gustav Kirchhoff]] and [[Robert Bunsen]] that each [[chemical element]] was associated with a set of spectral lines, and deduced that the dark lines in the solar spectrum were caused by [[absorption (optics)|absorption]] by those elements in the upper layers of the sun. Some of the observed features are also caused by absorption in [[oxygen]] molecules in the [[Earth's atmosphere]].
+The major Fraunhofer lines, and the elements they are associated with, are shown in the following table:
+<table class="wikitable">
+<tr><th> Designation <th> Element <th> Wavelength ([[nanometer|nm]])
+<th><th> Designation <th> Element <th> Wavelength (nm)
+<tr><td>y<td>[[Oxygen|O<sub>2</sub>]]<td>898.765
+<td><td>c<td>Fe<td>495.761
+<tr><td>Z<td>O<sub>2</sub><td>822.696
+<td><td>F<td>H β<td>486.134
+<tr><td>A<td>O<sub>2</sub><td>759.370
+<td><td>d<td>Fe<td>466.814
+<tr><td>B<td>O<sub>2</sub><td>686.719
+<td><td>e<td>Fe<td>438.355
+<tr><td>C<td>[[Hydrogen|H]] α<td>656.281
+<td><td>G'<td>H γ<td>434.047
+<tr><td>a<td>O<sub>2</sub><td>627.661
+<td><td>G<td>Fe<td>430.790
+<tr><td>D<sub>1</sub><td>[[Sodium|Na]]<td>589.592
+<td><td>G<td>[[Calcium|Ca]]<td>430.774
+<tr><td>D<sub>2</sub><td>Na<td>588.995
+<td><td>h<td>H δ<td>410.175
+<tr><td>D<sub>3</sub> (or d)<td>[[Helium|He]]<td>587.5618
+<td><td>H<td>Ca<sup>+</sup><td>396.847
+<tr><td>e<td>[[Mercury (element)|Hg]]<td>546.073
+<td><td>K<td>Ca<sup>+</sup><td>393.368
+<tr><td>E<sub>2</sub><td>[[Iron|Fe]]<td>527.039
+<td><td>L<td>Fe<td>382.044
+<tr><td>b<sub>1</sub><td>[[Magnesium|Mg]]<td>518.362
+<td><td>N<td>Fe<td>358.121
+<tr><td>b<sub>2</sub><td>Mg<td>517.270
+<td><td>P<td>[[Titanium|Ti]]<sup>+</sup><td>336.112
+<tr><td>b<sub>3</sub><td>Fe<td>516.891
+<td><td>T<td>Fe<td>302.108
+<tr><td>b<sub>4</sub><td>Fe<td>516.751
+<td><td>t<td>[[Nickel|Ni]]<td>299.444
+<tr><td>b<sub>4</sub><td>Mg<td>516.733
+</table>
+Given their well-defined wavelengths, Fraunhofer lines are often used to characterize the [[refractive index]] and [[dispersion (optics)|dispersion]] properties of optical materials.<ref>The Fraunhofer C-, F-, G'-, and h- lines correspond to the alpha, beta, gamma and delta lines of the [[Balmer series]] of [[emission line]]s of the hydrogen atom. The D<sub>1</sub> and D<sub>2</sub> lines form the well-known "sodium doublet," the center wavelength of which (587.5618 nm) is given the designation letter "D." There is disagreement in the literature for some line designations; e.g., the Fraunhofer d-line may refer to the [[cyan]] iron line at 466.814 nm, or alternatively to the [[yellow]] helium line (also labeled D<sub>3</sub>) at 587.5618 nm. Similarly, there is ambiguity with reference to the e-line, since it can refer to the spectral lines of both iron (Fe) and mercury (Hg). To resolve ambiguities that arise in usage, ambiguous Fraunhofer line designations are preceded by the element with which they are associated (e.g., Mercury e-line and Helium d-line).</ref>
 ==See also==
-* [[Fraunhofer society]]
-* [[Fraunhofer diffraction]]
+* [[Optics]]
+* [[Spectroscopy]]
 * [[Fraunhofer line]]
+* [[Timeline of solar astronomy]]
+* [[Balmer series]]
+== Notes ==
+<references/>
 == References ==
 *{{cite book | author=Aller, Lawrence H. | title=Atoms, Stars and Nebulae, 3rd ed. | publisher=Cambridge University Press | year=1991 | id=ISBN 0-521-32512-9}}
 ==External links==
 *[http://www.hao.ucar.edu/Public/education/bios/fraunhofer.html Biography of Joseph von Fraunhofer]
 *[http://www.newadvent.org/cathen/06250a.htm Catholic Encyclopedia article on Joseph von Fraunhofer]
-[[Category:1787 births|Fraunhofer, Joseph von]]
+[[Category:Physical sciences]]
-[[Category:1826 deaths|Fraunhofer, Joseph von]]
+[[Category:Biographies of Scientists and Inventors]]
-[[Category:German astronomers|Fraunhofer, Joseph von]]
+[[Category:Astronomy]]
-[[Category:German nobility|Fraunhofer, Joseph von]]
+[[Category:Physics]]
-[[Category:German physicists|Fraunhofer, Joseph von]]
+[[Category:Biography]]
-[[Category:Instrument makers|Fraunhofer, Joseph von]]
-[[bn:ইয়োসেফ ফন ফ্রাউনহোফার]]
+{{credits|Joseph_von_Fraunhofer|120698763}}
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