Study of Fraunhofer Diffraction Pattern Using Frequency Image Processing

Authors:Jimy Alexander Cortes and Jairo Alberto Mendoza Vargas

Source:FERMAT, Volume 6, Communications 13, Nov Dec.,2014

Abstract: Any type of energy that travels in a waveform is capable of bending around obstacles, but this is more evident when the obstacle is comparable in size to the energy's wavelength. Light, as a wave, is diffracted and its analysis is a hot topic in engineering due to its applications in scientific instrumentation and the foundation of quantum theory and its particle wavelength properties. This paper introduces an alternative classroom way to present the link between far- field diraction of an incident plane wave, called Fraunhofer diraction and the Fourier Transform using image processing techniques in the laboratory and classroom to undergraduate physics and engineering students using Freemat, a free clone of the highly popular scientific numerical analysis software, Matlab. We propose experiments for a single slit and a circular aperture (Airy Disk) which are analyzed using a digital photographic camera as the instrument and three different wavelength (650nm red, 532nm green and 405nm violet) low cost, low power (5mW) laser pointers as light samples. These experiments over an alternative laboratory and classroom implementation which allows evaluation of Fraunhofer diraction with a relative error of less than 3% compared to the ideal two dimensional Fast Fourier Transform and present a cross-relation between two apparently separate topics for physics and engineering students. Even though this kind of didactic strategies are applicable for all countries for teaching Fraunhofer Diraction, they are more suitable for third world countries where complex and expensive laboratory setups cannot be afforded

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Study of Fraunhofer Diffraction Pattern Using Frequency Image Processing