Digital coronagraph algorithm

The detection of faint stellar companions requires high contrast techniques such as coronagraphy. To achieve such high contrast coronagraphs must work with the aid of adaptive optics or be mounted on space telescopes. We propose a new coronagraphic technique that consists of the digital processing of non-coronagraphic images. The only requirement is a priori knowledge of the telescope amplitude point spread function. This digital coronagraph algorithm presents the advantage that it avoids problems associated with manufacture, implementation, and alignment of optical coronagraphs. The digital coronagraph algorithm is successfully checked with laboratory generated images. Moreover, numerical simulations show that the digital coronagraph presents contrast curves similar to that of the optical coronagraph. Finally, speckle noise can be cancelled out as effectively as in optical coronagraphs.