Análisis del comportamiento de membranas semitransparentes frente a incidencia oblicua de haces gaussianos con modos superiores

There are two main possibilities that are being considered for the ALMA calibration system. The first one consists in a polarizing grid used as beam splitter. The second one consists in a semitransparent vane, a more feasible system but less accurate, which is now under test. This paper introduces an analysis of this kind of devices with the intention of advancing into the knowledge of the vane features and improving its accuracy in this manner. Therefore, a study about its response to oblique incidence is developed. Together with a beam mode expansion into gaussian higher order modes over the fields that impinge on the foam, observing its behaviour in contrast with fundamental mode analysis, taking into account the finite dimensions of the foam. By last, a study about effects of the incidence angle into power transmitted by the foam is presented.