Development and Demonstration of New Focal Plane Wavefront Sensing Techniques for High-Contrast Direct Imaging of Exoplanets

Abstract

With extremely large telescopes coming online over the next few decades, the ability to directly image and characterize Earth-like exoplanets is finally within reach. With state-of-the-art technology, coronagraphs and phase conjugation techniques are now capable of creating regions of high contrast, known as dark holes, within which light from an exoplanet can be made visible above the stellar signal at small separations from the star. This will allow for direct imaging of an exoplanet in reflected light. Maintaining the high-contrast within the dark hole to keep the exoplanet visible over long observation runs, however, has proven to be a challenge. In this dissertation, I demonstrate new methods of maintaining high-contrast to allow for continuous direct imaging of an exoplanet within the dark hole both in simulation and in laboratory experiments. These techniques, known as modal wavefront sensing (MWFS) and linear dark field control (LDFC), use the science image detector as the wavefront sensor and allow for precision monitoring of aberrations in the image that destroy the high-contrast within the dark hole and overwhelm the light from the exoplanet. With these algorithms, the dark hole contrast is stabilized, and the exoplanet remains visible for direct imaging over long observation periods. The substantial increase in uninterrupted observation time that MWFS and LDFC provide over current stabilization methods will result in an overall increase in the number of exoplanets detected and analyzed over the lifetime of an instrument, thereby bringing the current state of technology one step closer to finding and characterizing another Earth-like planet.