Abstract

With improvements in super-polished mirror technology, coronagraphs can be designed based on mirror objectives. Reflecting coronagraphs provide superior performance capabilities compared with classical singlet-lens-objective Lyot coronagraphs. Specifically, an all-reflecting design has the advantage of full achromaticity; wavelength coverage is limited only by atmospheric spectral transmittance, mirror reflectance, and detector response, and simple heat-flux rejection is inherent in the design. Further, large-aperture systems can be designed to be capable of producing high-angular-resolution imaging. A program to develop reflecting coronagraphs at NSO/SP is described, including the construction of two prototype instruments, of 5-cm and 15-cm apertures, respectively. In particular, applications in the infrared are emphasized; since strong spectral lines are available, the sky brightness is reduced, as are the scattering properties of super-polished surfaces. The advantages of some designs for certain nighttime applications, using either ground- or space-based systems, are discussed.

© 1992 Optical Society of America