Multi-stage four-quadrant phase mask: achromatic coronagraph for space-based and ground-based telescopes

Abstract

Less than 3% of the known exoplanets were directly imaged for two main reasons. They are angularly very close to their parent star, which is several magnitudes brighter. Direct imaging of exoplanets thus requires a dedicated instrumentation with large telescopes and accurate wavefront control devices for high-angular resolution and coronagraphs for attenuating the stellar light. Coronagraphs are usually chromatic and they cannot perform high-contrast imaging over a wide spectral bandwidth. That chromaticity will be critical for future instruments. Enlarging the coronagraph spectral range is a challenge for future exoplanet imaging instruments on both space-based and ground-based telescopes. We propose the multi-stage four-quadrant phase mask that associates several monochromatic four-quadrant phase mask coronagraphs in series. Monochromatic device performance has already been demonstrated and the manufacturing procedures are well-under control since their development for previous instruments on VLT and JWST. The multi-stage implementation simplicity is thus appealing. We present the instrument principle and we describe the laboratory performance for large spectral bandwidths and for both pupil shapes for space- (off-axis telescope) and ground-based (E-ELT) telescopes. The multi-stage four-quadrant phase mask reduces the stellar flux over a wide spectral range (30%) and it is a very good candidate to be associated with a spectrometer for future exoplanet imaging instruments in ground- and space-based observatories.

7 pages, 11 figures, 4 tables, accepted in A&A

References in corpus (2)

• Improved High Contrast Imaging with On-Axis Telescopes using a Multi-Stage Vortex Coronagraph
• Theory and laboratory tests of the multi-stage phase mask coronagraph

Cited by in corpus (8)

• Apodized Pupil Lyot Coronagraphs for Arbitrary Apertures. IV. Reduced Inner Working Angle and Increased Robustness to Low-Order Aberrations
• High-contrast imaging in polychromatic light with the self-coherent camera
• Apodized phase mask coronagraphs for arbitrary apertures. II. Comprehensive review of solutions for the vortex coronagraph
• Apodized phase mask coronagraphs for arbitrary apertures
• Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph
• A Family of Phase Masks For Broadband Coronagraphy Example of the Wrapped Vortex Phase Mask Theory and Laboratory demonstration
• Imaging exoplanets with coronagraphic instruments
• Laboratory validation of the dual-zone phase mask coronagraph in broadband light at the high-contrast imaging THD-testbed