Near-Field Diffraction Analysis: Diffraction behind the slit is studied using the families of curves in the half-wave slit model

[size=85] In the half-wave slit[url=https://www.geogebra.org/m/n62bumu7] model[/url], [b]we define[/b] the [b]family of curves[/b] passing through the intensity field extrema behind the slit as 'extremal' (or 'stationary') lines.[br] You will find images created using this applet in [[url=https://www.geogebra.org/m/yzx8p6bk]1[/url]].[/size]
Location of Extremal Line Intersections
[size=85] In the half-wave slit model, the near-field (Fresnel) diffraction field behind a slit ([b]b = 6[/b], [b]λ = 1[/b]) is structured by a family of continuous [i]extremal[/i] (or [i]stationary[/i]) lines. The intersections of these lines correspond to critical points ([b]local maxima[/b], [b]minima[/b], or [b]saddle[/b] points) in the intensity distribution[b] J(x, y)[/b], which define the [b][i]exact conditions[/i][/b] for [b][i]destructive[/i][/b] and [b][i]constructive[/i][/b] [b]interference[/b] of waves from half-wave zones.[/size]
– Roman Chijner

Information: Near-Field Diffraction Analysis: Diffraction behind the slit is studied using the families of curves in the half-wave slit model