Mehrstrahlinterferenz und Eigenwellen im Parallelspiegel-Interferometer

Experiments with a Fabry Perot interferometer for microwaves (λ=3,2 cm) at oblique incidence show the importance of oscillation modes (well known from laser research) for the formation of multiple-beam interferences. A general formula is derived describing diffraction and multiple-beam interference in an interferometer with parallel mirrors of finite diameter. The formula is in quantitative agreement with the experimental results and includes as special cases the Fraunhofer diffraction at a slit and also the conventional multiple-beam interference (Fabry Perot rings).