Fourier transform of periodic structures

Mathematical description of Fourier transform of the periodic structure. We introduce the concept of the Fourier series and we investigate the Dirichlet kernel. We also introduce the concept of distributions, the Fourier transform and convolution. Using this we discover the properties of the Dirac's delta, the Dirac comb and then we define the periodic structure. In conclusion, we mention the dual lattice. The thesis is designed to contain physical notes. Some of proofs are formal