Dissertation
Focal-plane wavefront sensors for direct exoplanet imaging: Theory, simulations and on-sky demonstrations
One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) to which the primary adaptive optics system is inherently blind. The main focus of this thesis is the development and (on-sky) testing of integrated coronagraph and focal-plane wavefront-sensing solutions to deal with NCPA.
- Author
- Bos, S.P.
- Date
- 30 September 2021
- Links
- Thesis in Leiden Repository
One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) to which the primary adaptive optics system is inherently blind. The main focus of this thesis is the development and (on-sky) testing of integrated coronagraph and focal-plane wavefront-sensing solutions to deal with NCPA. First, we enable focal-plane wavefront sensing with vector-Apodizing Phase Plate coronagraph by integrating a pupil-plane amplitude asymmetry into the design. Low-order wavefront sensing is then demonstrated with a non-linear model-based algorithm and high-order wavefront with spatial Linear Dark Field Control. We introduce the polarization-encoded self-coherent camera, which is a new and more powerful variant of the self-coherent camera. Furthermore, we show through on-sky tests that the “Fast and Furious” focal-plane wavefront sensing algorithm is capable of measured and controlling the low-wind effect. Lastly, the vector speckle grid is presented and dramatically increases the signal-to-noise ration of exoplanet variability measurements. The ultimate goal of this thesis is to enable the direct imaging and characterization of rocky exoplanets with future extremely large telescopes.