Introduction to stellar coronagraphy with entrance pupil apodization

Abstract
The general formalism for Lyot and Roddier & Roddier coronagraphy is detailed. The influence of the mask size, chromatism and central obscuration are discussed. The necessity of entrance pupil apodization for coronagraphy is introduced from the fundamental limitation that appears in the classical technique. Prolate spheroidal functions are presented as the natural apodizations for coronagraphy.