Authors

Mamadou N’Diaye, Kjetil Dohlen, Salvador Cuevas, Rémi Soummer, Celia Sánchez

Affiliations

LAM, IA-UNAM, STScI and CCADET-UNAM

Abstract

Stellar coronagraphy is a key technology for current and future instruments for exoplanet imaging and spectroscopy, both on the ground and in space. In this context, phase mask stellar coronagraphs constitute some very interesting coronagraphic solutions for these instruments since they enable the observation very close to a bright star. We pursue the research on the Dual Zone Phase Mask (DZPM) coronagraph, a concept which aims to attenuate efficiently the brightness of an observed star over a wide range of wavelengths. The DZPM coronagraph is composed of an apodizer in the entrance pupil plane, a slightly defocused DZPM and a Lyot stop in the re-imaged pupil plane. We propose a modification of this concept, replacing the traditional grey apodizer by a colored one. Chromatic optimization of the apodization transmission function is performed to reach the best suppression of the stellar diffraction pattern over a large spectral bandwidth, and physical designs using existing materials and technologies are investigated. Performance obtained with our DZPM coronagraph design using a colored apodization is reported in terms of the trade between spectral bandwidth and achievable contrast, and manufacturing aspects are detailed. The use of DZPM coronagraph as a wavefront sensor for the measurement of quasi static aberrations is also investigated. We present the concept and show initial simulation results.