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Undergraduate Projects

  • Improvements of measuring the width of Fraunhofer diffraction fringes using Fourier transform

Fourier Domain

Abstract: In this paper, we proposed an improved method for calculating the fringe width of Fraunhofer diffraction. Because the diffraction patterns are equidistant when the diffraction angle is small, the width of fringes can be determined through finding out the spatial frequency of the fringes using Fourier transform. To make the result more precise, the experimental data are compared with the theoretical values having the same range of the image in the frequency domain to get the modified frequency. We applied this method to calculate the diameters of some filaments by measuring their Fraunhofer diffraction fringes.

Wu, Yicheng, et al. “Improvements of measuring the width of Fraunhofer diffraction fringes using Fourier transform.” Optik-International Journal for Light and Electron Optics 126.23 (2015): 4142-4145. PDF

  • Controlling the Wave Propagation through the Medium Designed by Linear Coordinate Transformation

Super Scattering: By coating designed media with a PEC object, the scattering of this object looks like a magnified object (1.5x).

Abstract: Based on the principle of transformation optics, we propose to control the wave propagating direction through the homogenous anisotropic medium designed by linear coordinate transformation. The material parameters of the medium are derived from the linear coordinate transformation applied. Keeping the space area unchanged during the linear transformation, the polarization-dependent wave control through a non-magnetic homogeneous medium can be realized. Beam benders, polarization splitter, and object illusion devices are designed, which have application prospects in micro-optics and nano-optics. The simulation results demonstrate the feasibilities and the flexibilities of the method and the properties of these devices. Design details and full-wave simulation results are provided. The work in this paper comprehensively applies the fundamental theories of electromagnetism and mathematics. The method of obtaining a new solution of the Maxwell equations in a medium from a vacuum plane wave solution and a linear coordinate transformation is introduced. These have a pedagogical value and are methodologically and motivationally appropriate for physics students and teachers at the undergraduate and graduate levels.

Wu, Yicheng, et al. “Controlling the wave propagation through the medium designed by linear coordinate transformation.” European Journal of Physics 36.1 (2014): 015006. PDF