Multi-aperture system crossing using the extended <i>ABCD</i> formalism and mode conversion

The aim of this paper is to solve the problem raised by the study of diffraction by a sequence of irises. Alternative methods to the diffraction integral, aimed at this problem, exist. However, these methods not only fail to provide results for the Fresnel region, but none of them address the scenario involving a large sequence of apertures. The method used here is simply based on mode conversion and the <i>ABCD</i> formalism. We first provide the method assessment by studying an arbitrary sequence of three apertures. Using the well-known diffraction integral and our method, the transverse field distribution beyond each aperture was determined, and the accuracy of the superposition was successfully confirmed. Going beyond the set of few aperture studies, already available in the literature, we give field distributions from diverse sequences with a significant number of irises. Different sizes, numbers, and distances between apertures are considered, and interesting field distributions are obtained. Advantages of this kind of optical system are illustrated in this paper.