2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/7255The last few years have seen a variety of new image mask designs for diffraction-limited coronagraphy. Could there still be useful designs as yet undiscovered? To begin to answer this question, I survey and unify the Fraunhofer theory of coronagraph image masks in the context of a one-dimensional classical coronagraph. I display a complete solution to the problem of removing on-axis light assuming an unapodized entrance aperture and I introduce the attenuation function, a measure of a generic coronagraph's off-axis performance. With these tools, I demonstrate that the masks proposed so far form a nearly complete library of image masks that are useful for detecting faint extrasolar planets.17 pages including 3 figures. Submitted to ApJ 1/13/04Astrophysicstext