Diffraction effects on very large space instruments: a detailed analysis to solar coronagraphy

Recent possibility of building clusters of micro-satellites have increased the interest on extremely large space instruments. Since this growing is not merely a change of scale, performance of these new instruments has to be critically re-analyzed under this new perspective. As an example, diffraction effects can lead to new levels of signal-to-noise ratio, greatly increasing the possible performance of classical optical instruments. In this work we have analyzed the diffraction behavior of an opaque disc acting as external occulter in a space solar coronagraph. Since the occulter can be set at great distance from the telescope, improvements on signal-to-noise ratio are obtained. Moreover, this analysis can lead to a determination of a potential apodization function for the occulter.