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<h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Fourieroptik</span></h1>
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<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="de" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="de" dir="ltr"><p>Die <b>Fourieroptik</b> (nach <a href="Jean_Baptiste_Joseph_Fourier" class="mw-redirect" title="Jean Baptiste Joseph Fourier">Jean Baptiste Joseph Fourier</a>) ist ein Teilbereich der <a href="Optik" title="Optik">Optik</a>, in dem die Ausbreitung von <a href="Licht" title="Licht">Licht</a> mit Hilfe der <a href="Fourier-Analysis" title="Fourier-Analysis">Fourier-Analyse</a> untersucht wird. Die Fourieroptik berücksichtigt die <a href="Elektromagnetische_Welle" title="Elektromagnetische Welle">Wellennatur</a> des Lichtes, vernachlässigt aber z. B. die <a href="Polarisation" title="Polarisation">Polarisation</a>.
</p><p>Die Fourieroptik beschreibt die Wechselwirkung von Lichtwellen mit optischen Systemen (z. B. Linsen, Blenden oder Gitter) durch die Anwendung der Fouriertransformation. Eine zweite Linse macht die Transformation der ersten Linse rückgängig. In der Brennebene der ersten Linse kann das Bild manipuliert werden. Durch Ausblenden können bestimmte Fourierkomponenten unterdrückt werden, wodurch eine Glättung der Bilder erreicht wird<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>.
</p>
<div class="mw-heading mw-heading2"><h2 id="Hintergrund">Hintergrund</h2></div>
<p>Die Grundlage der Fourieroptik ist die Feststellung, dass das <a href="Beugungsintegral#Fraunhofer-Näherung" title="Beugungsintegral">Fraunhofer-Beugungsmuster</a> der <a href="Fourier-Transformation" title="Fourier-Transformation">Fouriertransformierten</a> des <a href="Beugung_(Physik)" title="Beugung (Physik)">beugenden</a> Objekts entspricht.
</p><p>Fällt <a href="Koh%C3%A4renz_(Physik)" title="Kohärenz (Physik)">kohärentes</a> Licht mit der räumlichen <a href="Amplitude" title="Amplitude">Amplituden</a>verteilung <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{e}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
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</msub>
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<annotation encoding="application/x-tex">{\displaystyle E_{e}}</annotation>
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</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/ad0071ee83b9d8052de06309324c86f5a8387a40.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.714ex; height:2.509ex;" alt="{\displaystyle E_{e}}" loading="lazy"></span> auf eine Struktur mit der räumlichen <a href="Transmission_(Physik)" title="Transmission (Physik)">Transmissions</a>verteilung <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tau }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>τ<!-- τ --></mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \tau }</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/38a7dcde9730ef0853809fefc18d88771f95206c.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.202ex; height:1.676ex;" alt="{\displaystyle \tau }" loading="lazy"></span>, so ist die Feldverteilung unmittelbar hinter der beugenden Struktur:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{t}=E_{e}\cdot \tau .}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>t</mi>
</mrow>
</msub>
<mo>=</mo>
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
</mrow>
</msub>
<mo>⋅<!-- ⋅ --></mo>
<mi>τ<!-- τ --></mi>
<mo>.</mo>
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</mrow>
<annotation encoding="application/x-tex">{\displaystyle E_{t}=E_{e}\cdot \tau .}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/a1910168a7cd99872cea5bce351f5a582d3dbf8f.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:11.881ex; height:2.509ex;" alt="{\displaystyle E_{t}=E_{e}\cdot \tau .}" loading="lazy"></span></dd></dl>
<p>Im <a href="Nahfeld_und_Fernfeld_(Antennen)" title="Nahfeld und Fernfeld (Antennen)">Fernfeld</a> der Struktur gilt für die Amplitudenverteilung:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E(x,y)=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\cdot \operatorname {e} ^{-{\text{i}}2\pi (xx'+yy')/(\lambda z_{0})}\mathrm {d} x'\mathrm {d} y'.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
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<mi>E</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
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<mo stretchy="false">)</mo>
<mo>=</mo>
<mi>A</mi>
<mo stretchy="false">(</mo>
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<mo>⋅<!-- ⋅ --></mo>
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<mtext>i</mtext>
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<mi>π<!-- π --></mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
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<mi>x</mi>
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</msup>
<mo>+</mo>
<mi>y</mi>
<msup>
<mi>y</mi>
<mo>′</mo>
</msup>
<mo stretchy="false">)</mo>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mo stretchy="false">(</mo>
<mi>λ<!-- λ --></mi>
<msub>
<mi>z</mi>
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<mn>0</mn>
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<mi mathvariant="normal">d</mi>
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<annotation encoding="application/x-tex">{\displaystyle E(x,y)=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\cdot \operatorname {e} ^{-{\text{i}}2\pi (xx'+yy')/(\lambda z_{0})}\mathrm {d} x'\mathrm {d} y'.}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/d13d3a11290ffa59e094cf2913c1f1cb964b12ac.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -4.005ex; width:60.339ex; height:8.843ex;" alt="{\displaystyle E(x,y)=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\cdot \operatorname {e} ^{-{\text{i}}2\pi (xx'+yy')/(\lambda z_{0})}\mathrm {d} x'\mathrm {d} y'.}" loading="lazy"></span></dd></dl>
<p>Dabei ist
</p>
<ul><li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z_{0}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z_{0}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/9e72d1d86e86355892b39b8eb32b964834e113bf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.135ex; height:2.009ex;" alt="{\displaystyle z_{0}}" loading="lazy"></span> der Abstand von der beugenden Struktur</li>
<li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x,y}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
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<annotation encoding="application/x-tex">{\displaystyle x,y}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5ea0abffd33a692ded22accc104515a032851dff.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.519ex; height:2.009ex;" alt="{\displaystyle x,y}" loading="lazy"></span> die transversalen Koordinaten</li>
<li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle A}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>A</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle A}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/7daff47fa58cdfd29dc333def748ff5fa4c923e3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.743ex; height:2.176ex;" alt="{\displaystyle A}" loading="lazy"></span> ein Phasenfaktor.</li>
<li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \lambda }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>λ<!-- λ --></mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \lambda }</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/b43d0ea3c9c025af1be9128e62a18fa74bedda2a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.355ex; height:2.176ex;" alt="{\displaystyle \lambda }" loading="lazy"></span> die Wellenlänge</li></ul>
<p>Analog zur <a href="Frequenz" title="Frequenz">Frequenz</a> bei der zeitlichen <a href="Fouriertransformation" class="mw-redirect" title="Fouriertransformation">Fouriertransformation</a> definiert man die <a href="Ortsfrequenz" title="Ortsfrequenz">Raumfrequenzen</a>:
</p>
<dl><dd><dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\begin{aligned}\nu _{x}&:={\frac {x}{\lambda \cdot z_{0}}}\\\nu _{y}&:={\frac {y}{\lambda \cdot z_{0}}},\end{aligned}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mtable columnalign="right left right left right left right left right left right left" rowspacing="3pt" columnspacing="0em 2em 0em 2em 0em 2em 0em 2em 0em 2em 0em" displaystyle="true">
<mtr>
<mtd>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
</mtd>
<mtd>
<mi></mi>
<mo>:=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<mrow>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mrow>
</mfrac>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
</mtd>
<mtd>
<mi></mi>
<mo>:=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>y</mi>
<mrow>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mrow>
</mfrac>
</mrow>
<mo>,</mo>
</mtd>
</mtr>
</mtable>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle {\begin{aligned}\nu _{x}&:={\frac {x}{\lambda \cdot z_{0}}}\\\nu _{y}&:={\frac {y}{\lambda \cdot z_{0}}},\end{aligned}}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/1b8a201182556b1196c3e9bb4007f868420e9ea8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -4.471ex; margin-bottom: -0.2ex; width:13.47ex; height:10.509ex;" alt="{\displaystyle {\begin{aligned}\nu _{x}&:={\frac {x}{\lambda \cdot z_{0}}}\\\nu _{y}&:={\frac {y}{\lambda \cdot z_{0}}},\end{aligned}}}" loading="lazy"></span></dd></dl></dd></dl>
<p>es folgt
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \Rightarrow E(\nu _{x}(x),\nu _{y}(y))=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\operatorname {e} ^{-{\text{i}}2\pi (\nu _{x}x'+\nu _{y}y')}\mathrm {d} x'\mathrm {d} y'.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">⇒<!-- ⇒ --></mo>
<mi>E</mi>
<mo stretchy="false">(</mo>
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<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
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</msub>
<mo stretchy="false">(</mo>
<mi>x</mi>
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<mo>∫<!-- ∫ --></mo>
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<msub>
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<mrow class="MJX-TeXAtom-ORD">
<mtext>i</mtext>
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<mn>2</mn>
<mi>π<!-- π --></mi>
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<msub>
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</msup>
<mo><!-- --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="normal">d</mi>
</mrow>
<msup>
<mi>x</mi>
<mo>′</mo>
</msup>
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="normal">d</mi>
</mrow>
<msup>
<mi>y</mi>
<mo>′</mo>
</msup>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \Rightarrow E(\nu _{x}(x),\nu _{y}(y))=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\operatorname {e} ^{-{\text{i}}2\pi (\nu _{x}x'+\nu _{y}y')}\mathrm {d} x'\mathrm {d} y'.}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/489c9cb1eb4d4319a784debd6085d261c74dcdc9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -4.005ex; width:67.12ex; height:8.843ex;" alt="{\displaystyle \Rightarrow E(\nu _{x}(x),\nu _{y}(y))=A(x,y,z_{0})\cdot \int \limits _{-\infty }^{\infty }E_{t}(x',y')\operatorname {e} ^{-{\text{i}}2\pi (\nu _{x}x'+\nu _{y}y')}\mathrm {d} x'\mathrm {d} y'.}" loading="lazy"></span></dd></dl>
<p>Das Fernfeld ist also gegeben durch die zweidimensionale Fouriertransformierte <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\mathcal {F}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mrow class="MJX-TeXAtom-ORD">
<mi class="MJX-tex-caligraphic" mathvariant="script">F</mi>
</mrow>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle {\mathcal {F}}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/205d4b91000d9dcf1a5bbabdfa6a8395fa60b676.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.927ex; height:2.176ex;" alt="{\displaystyle {\mathcal {F}}}" loading="lazy"></span> des Felds <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{t}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>t</mi>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle E_{t}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/8e1f5f5ca535e7c0078278861ca5358b1ce80ba3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.541ex; height:2.509ex;" alt="{\displaystyle E_{t}}" loading="lazy"></span> unmittelbar hinter der beugenden Struktur:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E=A\cdot {\mathcal {F}}\left[E_{t}\right]\left(\nu _{x},\nu _{y}\right).}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>E</mi>
<mo>=</mo>
<mi>A</mi>
<mo>⋅<!-- ⋅ --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mrow class="MJX-TeXAtom-ORD">
<mi class="MJX-tex-caligraphic" mathvariant="script">F</mi>
</mrow>
</mrow>
<mrow>
<mo>[</mo>
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>t</mi>
</mrow>
</msub>
<mo>]</mo>
</mrow>
<mrow>
<mo>(</mo>
<mrow>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mo>,</mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
</mrow>
<mo>)</mo>
</mrow>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle E=A\cdot {\mathcal {F}}\left[E_{t}\right]\left(\nu _{x},\nu _{y}\right).}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/956978b72c5cded0a45199eacd472f414c1631e6.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:23.228ex; height:3.009ex;" alt="{\displaystyle E=A\cdot {\mathcal {F}}\left[E_{t}\right]\left(\nu _{x},\nu _{y}\right).}" loading="lazy"></span></dd></dl>
<div class="mw-heading mw-heading3"><h3 id="Bedeutung_der_Raumfrequenzen">Bedeutung der Raumfrequenzen</h3></div>
<p>Ein <a href="Strahl_(Geometrie)" title="Strahl (Geometrie)">Strahl</a> vom Punkt <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (x,y,z_{0})}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
<mo>,</mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (x,y,z_{0})}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/e1956b792b795ef7cb27a17857e3973754b64584.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.498ex; height:2.843ex;" alt="{\displaystyle (x,y,z_{0})}" loading="lazy"></span> in der Beobachtungsebene bis zum Punkt <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (0,0,0)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mn>0</mn>
<mo>,</mo>
<mn>0</mn>
<mo>,</mo>
<mn>0</mn>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (0,0,0)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/28c6fd55d5621fd95ca93549660fbb355fd9bd22.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:7.365ex; height:2.843ex;" alt="{\displaystyle (0,0,0)}" loading="lazy"></span> in der Ebene der beugenden Struktur schließt mit der <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>z</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/bf368e72c009decd9b6686ee84a375632e11de98.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.088ex; height:1.676ex;" alt="{\displaystyle z}" loading="lazy"></span>-Achse folgende Winkel ein:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \tan(\alpha )={\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \tan(\beta )={\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>tan</mi>
<mo><!-- --></mo>
<mo stretchy="false">(</mo>
<mi>α<!-- α --></mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mfrac>
</mrow>
<mo>=</mo>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mspace width="2em"></mspace>
<mi>tan</mi>
<mo><!-- --></mo>
<mo stretchy="false">(</mo>
<mi>β<!-- β --></mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>y</mi>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mfrac>
</mrow>
<mo>=</mo>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \tan(\alpha )={\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \tan(\beta )={\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/2ba4f4fca6564712809aecea7eaf92a3f9e98176.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:47.761ex; height:5.176ex;" alt="{\displaystyle \tan(\alpha )={\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \tan(\beta )={\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}" loading="lazy"></span></dd></dl>
<p>Für nicht zu große Winkel (also für nicht zu große <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x,y}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle x,y}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5ea0abffd33a692ded22accc104515a032851dff.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.519ex; height:2.009ex;" alt="{\displaystyle x,y}" loading="lazy"></span>) folgt hieraus (<a href="Kleinwinkeln%C3%A4herung" title="Kleinwinkelnäherung">Kleinwinkelnäherung</a>):
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \alpha \approx {\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \beta \approx {\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>α<!-- α --></mi>
<mo>≈<!-- ≈ --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mfrac>
</mrow>
<mo>=</mo>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mspace width="2em"></mspace>
<mi>β<!-- β --></mi>
<mo>≈<!-- ≈ --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>y</mi>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mfrac>
</mrow>
<mo>=</mo>
<mi>λ<!-- λ --></mi>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \alpha \approx {\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \beta \approx {\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/f82099e5b28595e808721255f29e7df00aad9636.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.171ex; width:37.036ex; height:5.176ex;" alt="{\displaystyle \alpha \approx {\frac {x}{z_{0}}}=\lambda \cdot \nu _{x}\qquad \beta \approx {\frac {y}{z_{0}}}=\lambda \cdot \nu _{y}.}" loading="lazy"></span></dd></dl>
<p>Licht, das im Fernfeld nah der <a href="Optische_Achse_(Optik)" title="Optische Achse (Optik)">optischen Achse</a> liegt, entspricht also niedrigen Raumfrequenzen, während weiter außen liegendes Licht zu hohen Raumfrequenzen gehört.
</p><p>Feine Strukturen im Objekt, also solche, die sich räumlich schnell ändern, gehören zu hohen Raumfrequenzen; entsprechend stellen gröbere Strukturen kleinere Raumfrequenzen dar.
</p>
<div class="mw-heading mw-heading3"><h3 id="Typische_Anwendungen">Typische Anwendungen</h3></div>
<ol><li><b>Optische <a href="Bildverarbeitung" title="Bildverarbeitung">Bildverarbeitung</a></b>: Kantenfilter, Tiefpass, Hochpass im Fourierraum<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li>
<li><b><a href="Beugungsintegral" title="Beugungsintegral">Beugungstheorie</a></b>: Erklärt Interferenz- und Beugungsbilder (z. B. bei Gittern)</li>
<li><b><a href="Lichtmikroskop" title="Lichtmikroskop">Mikroskopie</a></b>: Auflösung als Begrenzung im Fourierraum</li>
<li><b><a href="Holographie" class="mw-redirect" title="Holographie">Holographie</a></b>: Speicherung und Rekonstruktion der komplexen Wellenfront</li>
<li><b>Laserstrahlformung</b>: Räumliche Tiefpassfilterung für einen sauberen <a href="Gau%C3%9F-Strahl" title="Gauß-Strahl">Gauß-Strahl</a><sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></li></ol>
<div class="mw-heading mw-heading2"><h2 id="Beispiel_Doppelspalt">Beispiel Doppelspalt</h2></div>
<p>Das beugende Objekt sei ein ebener Schirm mit zwei rechteckigen, spaltförmigen Öffnungen. Der Schirm liege in der <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z=0}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>z</mi>
<mo>=</mo>
<mn>0</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z=0}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/b92bfc06485cc90286474b14a516a68d8bfdd7b3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.349ex; height:2.176ex;" alt="{\displaystyle z=0}" loading="lazy"></span> Ebenen. Die Ränder der Spalten verlaufen parallel zur y- bzw. x-Achse. Die Mittelpunkte der beiden Spalten liegen auf der x-Achse bei <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (d/2,0,0)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo>,</mo>
<mn>0</mn>
<mo>,</mo>
<mn>0</mn>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (d/2,0,0)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/9e72b930065cb2ac2291bd156de5b2940f2bc4cb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:9.743ex; height:2.843ex;" alt="{\displaystyle (d/2,0,0)}" loading="lazy"></span> bzw. <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (-d/2,0,0)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mo>−<!-- − --></mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo>,</mo>
<mn>0</mn>
<mo>,</mo>
<mn>0</mn>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (-d/2,0,0)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/fd23c5886300717a8027a78f09e1ddae5beedb55.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:11.551ex; height:2.843ex;" alt="{\displaystyle (-d/2,0,0)}" loading="lazy"></span>, der Abstand der Mittelpunkte beträgt also <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>d</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle d}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/e85ff03cbe0c7341af6b982e47e9f90d235c66ab.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}" loading="lazy"></span>. Die Breiten beider Spalte in x-Richtung haben den gleichen Wert <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle a}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>a</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle a}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/ffd2487510aa438433a2579450ab2b3d557e5edc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.23ex; height:1.676ex;" alt="{\displaystyle a}" loading="lazy"></span> und ihre Ausdehnungen in y-Richtung haben ebenso gleich große Werte, nämlich <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle b}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>b</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle b}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/f11423fbb2e967f986e36804a8ae4271734917c3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.998ex; height:2.176ex;" alt="{\displaystyle b}" loading="lazy"></span>. Für den Abstand der Spaltenmittelpunkte wird <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d>a}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>d</mi>
<mo>></mo>
<mi>a</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle d>a}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5a63ce3b01161f8f4a757d6d8e0408dcdbe5b478.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.544ex; height:2.176ex;" alt="{\displaystyle d>a}" loading="lazy"></span> vorausgesetzt, somit ist der durchlässige Bereich der Blende durch zwei rechteckigen Öffnungen definiert:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle -b/2<y<b/2\quad }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo>−<!-- − --></mo>
<mi>b</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo><</mo>
<mi>y</mi>
<mo><</mo>
<mi>b</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mspace width="1em"></mspace>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle -b/2<y<b/2\quad }</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/cb77bccc000e461283abd6e5777abd7bb577d1ed.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.128ex; height:2.843ex;" alt="{\displaystyle -b/2<y<b/2\quad }" loading="lazy"></span> und <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \quad -a/2+p(d/2)<x<a/2+p(d/2)\quad }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mspace width="1em"></mspace>
<mo>−<!-- − --></mo>
<mi>a</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo>+</mo>
<mi>p</mi>
<mo stretchy="false">(</mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo stretchy="false">)</mo>
<mo><</mo>
<mi>x</mi>
<mo><</mo>
<mi>a</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo>+</mo>
<mi>p</mi>
<mo stretchy="false">(</mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo stretchy="false">)</mo>
<mspace width="1em"></mspace>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \quad -a/2+p(d/2)<x<a/2+p(d/2)\quad }</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/4d2991ead2e3434fd2eed973b2fae52254a3e69a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:39.809ex; height:2.843ex;" alt="{\displaystyle \quad -a/2+p(d/2)<x<a/2+p(d/2)\quad }" loading="lazy"></span> mit <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p=-1,1}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>p</mi>
<mo>=</mo>
<mo>−<!-- − --></mo>
<mn>1</mn>
<mo>,</mo>
<mn>1</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle p=-1,1}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/9ee3a24b557164ae2b17d6068f173e25b5d3ddf8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:9.524ex; height:2.509ex;" alt="{\displaystyle p=-1,1}" loading="lazy"></span></dd></dl>
<p>Einem solchen Schirm entspricht die Transmissionsfunktion:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{t}=E_{e}\cdot \tau =E_{e}\cdot \left[\delta (x+d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)+\delta (x-d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)\right]\operatorname {rect} \left({\frac {y}{b}}\right)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>t</mi>
</mrow>
</msub>
<mo>=</mo>
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
</mrow>
</msub>
<mo>⋅<!-- ⋅ --></mo>
<mi>τ<!-- τ --></mi>
<mo>=</mo>
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
</mrow>
</msub>
<mo>⋅<!-- ⋅ --></mo>
<mrow>
<mo>[</mo>
<mrow>
<mi>δ<!-- δ --></mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>+</mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo stretchy="false">)</mo>
<mo>∗<!-- ∗ --></mo>
<mi>rect</mi>
<mo><!-- --></mo>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<mi>a</mi>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mi>δ<!-- δ --></mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>−<!-- − --></mo>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mn>2</mn>
<mo stretchy="false">)</mo>
<mo>∗<!-- ∗ --></mo>
<mi>rect</mi>
<mo><!-- --></mo>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<mi>a</mi>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
</mrow>
<mo>]</mo>
</mrow>
<mi>rect</mi>
<mo><!-- --></mo>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>y</mi>
<mi>b</mi>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle E_{t}=E_{e}\cdot \tau =E_{e}\cdot \left[\delta (x+d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)+\delta (x-d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)\right]\operatorname {rect} \left({\frac {y}{b}}\right)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/86b949bc46548498f79f91add15da49ddf4a1a1a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.005ex; width:75.968ex; height:5.009ex;" alt="{\displaystyle E_{t}=E_{e}\cdot \tau =E_{e}\cdot \left[\delta (x+d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)+\delta (x-d/2)*\operatorname {rect} \left({\frac {x}{a}}\right)\right]\operatorname {rect} \left({\frac {y}{b}}\right)}" loading="lazy"></span></dd></dl>
<p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \operatorname {rect} (x)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>rect</mi>
<mo><!-- --></mo>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \operatorname {rect} (x)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/7da0f0593d274a05d2e869554a994f8ec6786f18.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:7.02ex; height:2.843ex;" alt="{\displaystyle \operatorname {rect} (x)}" loading="lazy"></span> ist die <a href="Rechteckfunktion" title="Rechteckfunktion">Rechteckfunktion</a> und <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle *}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo>∗<!-- ∗ --></mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle *}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/8e9972f426d9e07855984f73ee195a21dbc21755.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: 0.079ex; margin-bottom: -0.25ex; width:1.162ex; height:1.509ex;" alt="{\displaystyle *}" loading="lazy"></span> der <a href="Faltung_(Mathematik)" title="Faltung (Mathematik)">Faltungsoperator</a>. Die Fouriertransformierte einer Faltung ist gleich dem Produkt der Fouriertransfomierten der gefalteten Funktionen. Die Rechteckfunktion hat als Fouriertransformierte eine <a href="Sinc-Funktion" title="Sinc-Funktion">Sinc-Funktion</a> und die Summe aus den beiden nach links bzw. rechts verschobenen Delta-Funktionen führen zu dem Cosinus in der folgenden Formel. Bei einer in Richtung <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>z</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/bf368e72c009decd9b6686ee84a375632e11de98.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.088ex; height:1.676ex;" alt="{\displaystyle z}" loading="lazy"></span> einfallenden ebenen Welle ist <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E_{e}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle E_{e}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/ad0071ee83b9d8052de06309324c86f5a8387a40.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.714ex; height:2.509ex;" alt="{\displaystyle E_{e}}" loading="lazy"></span> auf der Ebenen <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z=0}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>z</mi>
<mo>=</mo>
<mn>0</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z=0}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/b92bfc06485cc90286474b14a516a68d8bfdd7b3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.349ex; height:2.176ex;" alt="{\displaystyle z=0}" loading="lazy"></span> für alle <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x,y}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle x,y}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5ea0abffd33a692ded22accc104515a032851dff.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.519ex; height:2.009ex;" alt="{\displaystyle x,y}" loading="lazy"></span> gleich und konnte somit vor das Integral gezogen werden.
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle E(x,y)=A(x,y,z_{0})\cdot E_{e}\cdot ab\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)2\cos(\pi \nu _{x}d)\left({\frac {\sin \pi \nu _{y}b}{\pi \nu _{y}b}}\right)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>E</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<mi>A</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
<mo>,</mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mo stretchy="false">)</mo>
<mo>⋅<!-- ⋅ --></mo>
<msub>
<mi>E</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>e</mi>
</mrow>
</msub>
<mo>⋅<!-- ⋅ --></mo>
<mi>a</mi>
<mi>b</mi>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mrow>
<mi>sin</mi>
<mo><!-- --></mo>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>a</mi>
</mrow>
<mrow>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>a</mi>
</mrow>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
<mn>2</mn>
<mi>cos</mi>
<mo><!-- --></mo>
<mo stretchy="false">(</mo>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>d</mi>
<mo stretchy="false">)</mo>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mrow>
<mi>sin</mi>
<mo><!-- --></mo>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
<mi>b</mi>
</mrow>
<mrow>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
<mi>b</mi>
</mrow>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle E(x,y)=A(x,y,z_{0})\cdot E_{e}\cdot ab\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)2\cos(\pi \nu _{x}d)\left({\frac {\sin \pi \nu _{y}b}{\pi \nu _{y}b}}\right)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/39cc96e2c03529a56ee0c5a372216160a115111d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:65.653ex; height:6.509ex;" alt="{\displaystyle E(x,y)=A(x,y,z_{0})\cdot E_{e}\cdot ab\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)2\cos(\pi \nu _{x}d)\left({\frac {\sin \pi \nu _{y}b}{\pi \nu _{y}b}}\right)}" loading="lazy"></span></dd></dl>
<p>Daraus folgt für die <a href="Intensit%C3%A4t_(Physik)#Intensität_in_der_Wellenlehre" title="Intensität (Physik)">Intensität</a> auf einem Beobachtungsschirm parallel zu einer <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x,y}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle x,y}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5ea0abffd33a692ded22accc104515a032851dff.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.519ex; height:2.009ex;" alt="{\displaystyle x,y}" loading="lazy"></span>-Ebenen bei <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z=z_{0}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>z</mi>
<mo>=</mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z=z_{0}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/5f8e63a3f2769739a78c3c24a091f778fdc72dfe.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:6.322ex; height:2.009ex;" alt="{\displaystyle z=z_{0}}" loading="lazy"></span> im Fernfeld bei großem Abstand, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle z_{0}\gg d^{2}/\lambda }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mo>≫<!-- ≫ --></mo>
<msup>
<mi>d</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
</mrow>
</msup>
<mrow class="MJX-TeXAtom-ORD">
<mo>/</mo>
</mrow>
<mi>λ<!-- λ --></mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle z_{0}\gg d^{2}/\lambda }</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/52a13a6d61cc384a34a9d2fc31b62d18beca2d8a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.539ex; height:3.176ex;" alt="{\displaystyle z_{0}\gg d^{2}/\lambda }" loading="lazy"></span> in der Mitte bei <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle y=0}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>y</mi>
<mo>=</mo>
<mn>0</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle y=0}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/094f824655138f6b11d96a0da32e7f0716ba6959.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.416ex; height:2.509ex;" alt="{\displaystyle y=0}" loading="lazy"></span> der folgende Intensitätsverlauf:
</p>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I(\nu _{x}(\alpha ))=I_{0}\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)^{2}\cos ^{2}(\pi \nu _{x}d)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>I</mi>
<mo stretchy="false">(</mo>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mo stretchy="false">(</mo>
<mi>α<!-- α --></mi>
<mo stretchy="false">)</mo>
<mo stretchy="false">)</mo>
<mo>=</mo>
<msub>
<mi>I</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<msup>
<mrow>
<mo>(</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mrow>
<mi>sin</mi>
<mo><!-- --></mo>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>a</mi>
</mrow>
<mrow>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>a</mi>
</mrow>
</mfrac>
</mrow>
<mo>)</mo>
</mrow>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
</mrow>
</msup>
<msup>
<mi>cos</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
</mrow>
</msup>
<mo><!-- --></mo>
<mo stretchy="false">(</mo>
<mi>π<!-- π --></mi>
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mi>d</mi>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle I(\nu _{x}(\alpha ))=I_{0}\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)^{2}\cos ^{2}(\pi \nu _{x}d)}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/8d740e725c06bb49ee09c668128060089835fa5e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:38.442ex; height:6.509ex;" alt="{\displaystyle I(\nu _{x}(\alpha ))=I_{0}\left({\frac {\sin \pi \nu _{x}a}{\pi \nu _{x}a}}\right)^{2}\cos ^{2}(\pi \nu _{x}d)}" loading="lazy"></span></dd></dl>
<p>Dabei ist <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle I_{0}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>I</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle I_{0}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/893d08e90ea73781dc133414d661529d0651ca80.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.077ex; height:2.509ex;" alt="{\displaystyle I_{0}}" loading="lazy"></span> die Intensität bei <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (x,y,z)=(0,0,z_{0})}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
<mi>y</mi>
<mo>,</mo>
<mi>z</mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<mo stretchy="false">(</mo>
<mn>0</mn>
<mo>,</mo>
<mn>0</mn>
<mo>,</mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (x,y,z)=(0,0,z_{0})}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/24ffe8d351ee82323a3d1244a4c64e1e6693cb2b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.886ex; height:2.843ex;" alt="{\displaystyle (x,y,z)=(0,0,z_{0})}" loading="lazy"></span>. Zu einem Punkt <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (x,0,z_{0})}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo>,</mo>
<mn>0</mn>
<mo>,</mo>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (x,0,z_{0})}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/41e8f943076a592f354ab4c8960e7bbed4618ecc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.505ex; height:2.843ex;" alt="{\displaystyle (x,0,z_{0})}" loading="lazy"></span> auf dem Beobachtungsschirm gehören die Werte <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \nu _{x}\approx {\frac {x}{z_{0}\lambda }}={\frac {\alpha }{\lambda }}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>x</mi>
</mrow>
</msub>
<mo>≈<!-- ≈ --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>x</mi>
<mrow>
<msub>
<mi>z</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>0</mn>
</mrow>
</msub>
<mi>λ<!-- λ --></mi>
</mrow>
</mfrac>
</mrow>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mfrac>
<mi>α<!-- α --></mi>
<mi>λ<!-- λ --></mi>
</mfrac>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \nu _{x}\approx {\frac {x}{z_{0}\lambda }}={\frac {\alpha }{\lambda }}}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/40e8a04f9e0b70a6c1c1d4ccbf9009464739e2bf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:15.168ex; height:5.176ex;" alt="{\displaystyle \nu _{x}\approx {\frac {x}{z_{0}\lambda }}={\frac {\alpha }{\lambda }}}" loading="lazy"></span> und <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \nu _{y}=0}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>ν<!-- ν --></mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>y</mi>
</mrow>
</msub>
<mo>=</mo>
<mn>0</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \nu _{y}=0}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/930f1bbf76a5244d9def73d95a3ec4d3790ae665.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:6.459ex; height:2.843ex;" alt="{\displaystyle \nu _{y}=0}" loading="lazy"></span>.
</p><p>Der Faktor mit dem quadrierten Cosinus beschreibt eine abwechselnden Folge von Intensitätsmaxima und Punkten mit der Intensität null, wobei die Abstände der Nullstellen durch den Abstand <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>d</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle d}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/e85ff03cbe0c7341af6b982e47e9f90d235c66ab.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}" loading="lazy"></span> der Spaltenmittelpunkte bestimmt wird. Der Faktor mit der quadrierten Sinc-Funktion definiert eine Einhüllende, die die Höhe der Maxima links und rechts von der Mitte nach außen hin abschwächen, die Schnelligkeit der Abschwächung wird durch die Breite <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle a}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>a</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle a}</annotation>
</semantics>
</math></span><img src="./_assets_/eb734a37dd21ce173a46342d1cc64c92/ffd2487510aa438433a2579450ab2b3d557e5edc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.23ex; height:1.676ex;" alt="{\displaystyle a}" loading="lazy"></span> der Spalten bestimmt, je breiter die beiden Spalten sind, desto schneller vermindert sich die Intensität zu den Seiten hin. Dieser hier angegebene Intensitätsverlauf steht im Zentrum bei der Auswertung von <a href="Doppelspaltexperiment" title="Doppelspaltexperiment">Doppelspaltexperimenten</a>.
</p>
<div class="mw-heading mw-heading2"><h2 id="Literatur">Literatur</h2></div>
<ul><li><a href="Joseph_W._Goodman" title="Joseph W. Goodman">Joseph W. Goodman</a>: <i>Introduction to Fourier optics.</i> 3rd edition. Roberts & Co., Englewood CO 2005, ISBN 0-9747077-2-4.</li>
<li>Wolfgang Stößel: <i>Fourieroptik. Eine Einführung.</i> Mit 47 Übungsaufgaben und Lösungen. Springer, Berlin u. a. 1993, ISBN 3-540-53287-0.</li>
<li><a href="Eugene_Hecht" title="Eugene Hecht">Eugene Hecht</a>: <i>Optik.</i> 4. Auflage. Oldenbourg, München 2005, ISBN 3-486-27359-0.</li></ul>
<div class="mw-heading mw-heading2"><h2 id="Siehe_auch">Siehe auch</h2></div>
<ul><li><a href="Beugungsintegral" title="Beugungsintegral">Beugungsintegral</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="Einzelnachweise">Einzelnachweise</h2></div>
<ol class="references">
<li id="cite_note-1"><span class="mw-cite-backlink"><a href="#cite_ref-1">↑</a></span> <span class="reference-text">Dieter Meschede: <cite style="font-style:italic">Optik, Licht und Laser</cite>. 3. Auflage. Vieweg + Teubner, Wiesbaden 2008, ISBN 978-3-8351-0143-2, <span style="white-space:nowrap">S.<span style="display:inline-block;width:.2em"> </span>73</span>.<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rfr_id=info:sid/de.wikipedia.org:Fourieroptik&rft.au=Dieter+Meschede&rft.btitle=Optik%2C+Licht+und+Laser&rft.date=2008&rft.edition=3.&rft.genre=book&rft.isbn=9783835101432&rft.pages=73&rft.place=Wiesbaden&rft.pub=Vieweg+%2B+Teubner" style="display:none"> </span></span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><a href="#cite_ref-2">↑</a></span> <span class="reference-text">Miles V. Klein, Thomas E. Furtak: <cite style="font-style:italic">Optics</cite>. 2. Auflage. Wiley, New York 1986, ISBN 0-471-84311-3, <span style="white-space:nowrap">S.<span style="display:inline-block;width:.2em"> </span>480</span>.<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rfr_id=info:sid/de.wikipedia.org:Fourieroptik&rft.au=Miles+V.+Klein%2C+Thomas+E.+Furtak&rft.btitle=Optics&rft.date=1986&rft.edition=2.&rft.genre=book&rft.isbn=0471843113&rft.pages=480&rft.place=New+York&rft.pub=Wiley" style="display:none"> </span></span>
</li>
<li id="cite_note-3"><span class="mw-cite-backlink"><a href="#cite_ref-3">↑</a></span> <span class="reference-text">Miles V. Klein, Thomas E. Furtak: <cite style="font-style:italic">Optics</cite>. 2. Auflage. Wiley, New York 1986, ISBN 0-471-84311-3, <span style="white-space:nowrap">S.<span style="display:inline-block;width:.2em"> </span>482</span>.<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rfr_id=info:sid/de.wikipedia.org:Fourieroptik&rft.au=Miles+V.+Klein%2C+Thomas+E.+Furtak&rft.btitle=Optics&rft.date=1986&rft.edition=2.&rft.genre=book&rft.isbn=0471843113&rft.pages=482&rft.place=New+York&rft.pub=Wiley" style="display:none"> </span></span>
</li>
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