Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph

Abstract

The vortex coronagraph is an optical instrument that precisely removes on-axis starlight allowing for high contrast imaging at small angular separation from the star, thereby providing a crucial capability for direct detection and characterization of exoplanets and circumstellar disks. Telescopes with aperture obstructions, such as secondary mirrors and spider support structures, require advanced coronagraph designs to provide adequate starlight suppression. We introduce a phase-only Lyot-plane optic to the vortex coronagraph that offers improved contrast performance on telescopes with complicated apertures. Potential solutions for the European Extremely Large Telescope (E-ELT) are described and compared. Adding a Lyot-plane phase mask relocates residual starlight away from a region of the image plane thereby reducing stellar noise and improving sensitivity to off-axis companions. The phase mask is calculated using an iterative phase retrieval algorithm. Numerically, we achieve a contrast on the order of $10^{-6}$ for a companion with angular displacement as small as $4\lambda /D$ with an E-ELT type aperture. Even in the presence of aberrations, improved performance is expected compared to either a conventional vortex coronagraph or optimized pupil plane phase element alone.

6 pages, 7 figures, Accepted for publication in A&A

References in corpus (12)

• Optical spin-to-orbital angular momentum conversion in inhomogeneous anisotropic media
• The Gemini Planet Imager: First Light
• First On-Sky High Contrast Imaging with an Apodizing Phase Plate
• Lyot-based Low Order Wavefront Sensor for Phase-mask Coronagraphs: Principle, Simulations and Laboratory Experiments
• Post-coronagraphic tip-tilt sensing for vortex phase masks: the QACITS technique
• Optical vortex coronagraphs on ground-based telescopes
• Performance characterization of a broadband vector Apodizing Phase Plate coronagraph
• L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCam
• On-sky demonstration of low-order wavefront sensing and control with focal plane phase mask coronagraphs
• Apodized phase mask coronagraphs for arbitrary apertures. II. Comprehensive review of solutions for the vortex coronagraph
• Development of a subwavelength grating vortex coronagraph of topological charge 4 (SGVC4)
• Optimized focal and pupil plane masks for vortex coronagraphs on telescopes with obstructed apertures

Cited by in corpus (15)

• Imaging low-mass planets within the habitable zone of α Centauri
• Active correction of aperture discontinuities - optimized stroke minimization II: optimization for future missions
• Advancing European High-Contrast Imaging R&D Towards the Habitable Worlds Observatory
• Three years of harvest with the vector vortex coronagraph in the thermal infrared
• Active correction of aperture discontinuities - optimized stroke minimization I: a new adaptive interaction matrix algorithm
• Imaging exoplanets with coronagraphic instruments
• Phase Retrieval and Design with Automatic Differentiation
• Apodized vortex coronagraph designs for segmented aperture telescopes
• Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics
• Implementing focal-plane phase masks optimized for real telescope apertures with SLM-based digital adaptive coronagraphy
• The Single-mode Complex Amplitude Refinement (SCAR) coronagraph: I. Concept, theory and design
• High-contrast Demonstration of an Apodized Vortex Coronagraph
• Spectroscopic fourth-order coronagraph for the characterization of terrestrial planets at small angular separations from host stars
• Capabilities of ACAD-OSM, an active method for the correction of aperture discontinuities
• Redundant apodization for direct imaging of exoplanets I: Robustness to primary mirror segmentation-induced errors outside the segment diffraction limit