Interference and Diffraction

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Interference and Diffraction Image

Model Data

Type: classic pde

Physics Modes: custom equation

Keywords: pde diffraction helmholtz equation equation editing

The classic double-slit experiment considers a planar and periodic oscillating wave which hits and passes two narrow slits. Assuming the slits are narrow enough, the passing waves will bend and cause an interference pattern, while diffraction will attenuate the off axis resulting amplitude.

In the example the Helmholtz equation is used to model the wave phenomena

$$ -( \frac{\partial^2 A}{\partial x^2} + \frac{\partial^2 A}{\partial y^2} ) - k^2 A = 0 $$

where A is the amplitude of the wave,and k the wave number (k = 2·π/λ).

This model is available as an automated tutorial by selecting Model Examples and Tutorials… > Classic PDE > Interference and Diffraction from the File menu. Or alternatively, follow the linked step-by-step instructions.

FEATool Multiphysics Tutorial - Interference and Diffraction