This thesis aims to demonstrate how the achromatic nature and design flexibility of liquid-crystal optics can be used to improve high-contrast imaging instruments to facilitate detailed exoplanet... Show moreThis thesis aims to demonstrate how the achromatic nature and design flexibility of liquid-crystal optics can be used to improve high-contrast imaging instruments to facilitate detailed exoplanet characterization.Chapter 2 discusses the design, performance, and future development of the liquid-crystal vector-apodizing phase plate (vAPP) coronagraph, five of which have been installed in different instruments on current generation telescopes since 2016. In chapter 3 we use the achromatic nature of the vAPP in combination with the LBT/ALES integral field spectrograph to obtain the first ever thermal infrared spectrum of the inner three HR 8799 planets. In Chapter 4 and 8 we show that by combining multiple grating patterns to reduce the influence of polarization leakage, we can improve the performance of liquid-crystal coronagraphs. In Chapter 5 and 6 we enhance sparse aperture masking, capable of detecting companions beyond the diffraction limit, by using liquid-crystal phase masks to enable low-resolution spectroscopy and improve throughput. In Chapter 7 we demonstrate that a liquid-crystal Zernike wavefront sensor can accurately and efficiently measure phase and amplitude aberrations simultaneously, facilitating extreme contrasts. Together, the concepts presented in this thesis can be used to improve high-contrast imaging instruments of both ground-based and space-based observatories. Show less
The next generation of high-contrast imaging instruments on space-based observatories requires sophisticated wavefront sensing and control in addition to a high-performance coronagraph. This thesis... Show moreThe next generation of high-contrast imaging instruments on space-based observatories requires sophisticated wavefront sensing and control in addition to a high-performance coronagraph. This thesis aims to further our knowledge of coronagraphs and their integration into high-contrast imaging instruments. Chapter 2 presents a new algorithm for global optimization of the apodizing phase plate coronagraph. Chapters 3 and 4 present the theory, design and laboratory results of the SCAR coronagraph, which uses a phase plate and single-mode fibers. Chapter 5 presents the development of HCIPy, a software package in Python for high-contrast imaging. Chapters 7 and 8 present the theory, design and laboratory results of the PAPLC coronagraph, which uses a phase plate, knife-edge focal-plane mask and Lyot stop, and an integrated high-order wavefront sensor. These new coronagraphy and wavefront sensing concepts pave the way for improved high-contrast imaging instruments, both from ground-based and space-based observatories. Show less
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... Show moreThis 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. Show less
In the first part of this thesis, we present an adaptive optics implementation for multi-photon microscopy correcting sample-induced wavefront aberrations using either direct wavefront sensing to... Show moreIn the first part of this thesis, we present an adaptive optics implementation for multi-photon microscopy correcting sample-induced wavefront aberrations using either direct wavefront sensing to run a close-loop adaptive optics system (Chapter 3), or use a model-based sensorless approach to iteratively correct the wavefront aberrations (Chapter 4). In the second part we present an analysis of the disintegrating exoplanet KIC 12557548 b where we model the dust tail generated by the host star's induced evaporation of the planet in Chapter 5, and in Chapter 6 we investigate the eclipse of 1SWASP J140747.93-394542.6 observed by SuperWASP indicative of an exoplanet hosting a ring system and potentially exomoons Show less
