In a single-slit diffraction, what happens to the intensity pattern if the slit width becomes narrower and narrower?

  • 1
    $\begingroup$ Have you checked your book for the answer? This should be explained there. At least an equation should be given $\endgroup$ Mar 19, 2019 at 4:52

1 Answer 1


Experimental verification:

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These single slit diffraction patterns were photographed with a helium-neon laser as the light source and a micrometer-controlled single slit. The sketches of the slit widths at right were scaled to the difference between the first minima of the diffraction patterns. If the geometry is such that the small angle approximation is valid, the width of the pattern is inversely proportional to the slit width.

  • $\begingroup$ Generally for lasers with gaussian beams the divergence is proportional to $\frac{\lambda}{\pi\omega}$ and i'm guessing a similar relationship is found here (along the axis perpendicular to the slit) if not this exact phenomenon. $\endgroup$
    – DakkVader
    Mar 19, 2019 at 7:51

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