Painting with starlight : optical techniques for the high-contrast imaging of exoplanets

Leiden Repository

Painting with starlight : optical techniques for the high-contrast imaging of exoplanets

Type: Doctoral Thesis
Title: Painting with starlight : optical techniques for the high-contrast imaging of exoplanets
Author: Wilby, M.J.
Issue Date: 2018-11-27
Keywords: Exoplanets
High-contrast imaging
Direct imaging
Coronagraphs
Wavefront sensing
Adaptive optics
Abstract: This thesis describes the development and validation of new high-contrast imaging techniques, with the ultimate goal of enabling the next generation of instruments for ELT-class telescopes to directly image Earth-like extra-solar planets orbiting around nearby stars. In particular, we focus on developing new focal-plane wavefront sensing techniques and liquid crystal optics to achieve high-precision adaptive optics control which is capable of stabilising the entire instrument. We demonstrate that one such hybrid optical concept, the coronagraphic Modal Wavefront Sensor (cMWS), is capable of providing real-time, broadband (500-900 nm) control of non-common path aberrations during on-sky observation. We also demonstrate via both realistic simulations and laboratory testing that the focal-plane sensing technique of “Fast and Furious” phase diversity provides a robust, software-only solution to unforeseen, performance-limiting wavefront control issues such as the low-wind effect seen in the SPHERE instrument at the VLT. Lastly, we characterise the extinction profile of the VLT-SPHERE-IRDIS apodised Lyot coronagraph using observations of the minor planet Ceres, and use this to devise a calibration scheme which optimises the accuracy with which polarised signals from the innermost regions of protoplanetary disks may be retrieved.
Promotor: Supervisor: Keller C. Co-Supervisor: Kenworty M.
Faculty: Faculty of Science
University: Leiden University
Uri: urn:isbn:9789402812619
Handle: http://hdl.handle.net/1887/67531
 

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