Analytical and experimental investigations of the diffraction field of a Gaussian beam through a sequence of apertures: applicability of the beam mode expansion method.

The beam mode expansion method is used to approximate the diffraction field through a sequence of apertures for Gaussian beam incidence. Each aperture is assumed to be located in the Fraunhofer region. The results show good agreement with the experiment if the aperture radii are not too small compared to the field spread.