Double-slit interference
= Double-slit interference
{title2=$I=I_1+I_2+2\sqrt{I_1I_2}|\gamma_{12}|\cos\delta$}
<Double-slit interference> depends on the relative <wave phase> and <first-order optical coherence> of two collected fields. For equal separately measured intensities, the <interferometric visibility> is $|\gamma_{12}|$. A small source direction change $\vartheta_x$ introduces <phase difference> $2\pi D\vartheta_x/\lambda$ for projected <interferometric baseline> $D$.