![]() ![]() Let the mesh geometry be measured by the local coordinates x and y in a plane perpendicular to the direction of the light propagation, and let the image pattern be measured by the local coordinates u and v near the eye in a plane parallel to the mesh plane.Ī Fraunhofer diffraction pattern as a Fourier transform of a square aperture in a mesh curtain.Īccording to the Fraunhofer diffraction theory, then, we can calculate the image above simply by Fourier transforming the light transmission function, which is a periodic rectangular function if the mesh is square. To simplify the model, we assume the electric field of the lights is a plane wave of uniform intensity for instance, 1 V/m. In this example, we calculate an image of the light from a traffic light passing through a mesh curtain, shown below. Besides Fourier optics, we use Fourier transformation in Fraunhofer diffraction theory, signal processing for frequency pattern extraction, and image processing for noise reduction and filtering. The ability to implement the Fourier transformation in a simulation is a useful functionality for a variety of applications. Understanding Fourier Transformation with a Fraunhofer Diffraction Example Let’s see how to perform this integral type of preprocessing and postprocessing in COMSOL Multiphysics with a Fraunhofer diffraction example. In a more specific example, an electromagnetic wave focused by a Fourier lens is given by Fourier transforming the electromagnetic field amplitude at the lens entrance. In a previous blog post, we discussed simulating focused laser beams for holographic data storage. ![]()
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