ABSTRACT
Fourier theory is an important mathematical tool for the digital processing of interferograms. The fact that the Fourier transform of a real asymmetrical function is Hermitian is referred to as the Hermitian property of the spectrum of real functions. The periodic functions just described are represented by a sum of real sinusoidal functions. A complex function is Hermitian if the real part is symmetrical and the imaginary part is antisymmetrical. Complex functions are very important tools in Fourier theory. A consequence of this theorem is that the Fourier transform of any function with any kind of symmetry can be made to be real, imaginary, or complex by means of a proper translation of the function. The numerical computation of a Fourier transform takes an extremely long time even for modern powerful computers.
