Apodization Function -- from Wolfram MathWorld

An apodization function (also called a tapering function or window function) is a function used to smoothly bring a sampled signal down to zero at the edges of the sampled region. This suppresses leakage sidelobes which would otherwise be produced upon performing a discrete Fourier transform, but the suppression is at the expense of widening the lines, resulting in a decrease in the resolution. A number of apodization functions for symmetrical (two-sided) interferograms are summarized below,...