UC Santa Cruz

While the majority of exoplanets are currently detected using indirect methods of observation, the direct imaging method offers a way to characterize an exoplanet's atmosphere, chemical composition, density, temperature, and orbit. However, the use of direct imaging has so far been limited to studying a population of young (<500Myr), hot (>600K), massive (>2 Mjup) gas giants and brown dwarfs. In this thesis, I present my work to expand the set of directly imaged companions through observation and instrumentation development. The introduction provides an overview of the promise, challenges, and motivation for conducting exoplanet direct imaging. The inner chapters of the thesis are divided by subject area into two parts. Each observation/instrumentation module contains three chapters following the same format: (I) An "emerging techniques" introductory section that gives an overview of the sub-field; (II) Original research into the current performance capabilities and limitations of our methods and technologies; and (III) A "futures" section where I discuss the natural next steps of the sub-field.

In Part 1, I introduce the strategies and tools available for conducting targeted direct imaging observations -- a method to use supporting data to curate a direct imaging observation. I demonstrate how this targeted approach is implemented by conducting an HCI/RV survey of our fifth closest neighbor, Wolf 359. I use this data to quantify the current limits of conducting high-contrast imaging with Keck-NIRC2 in the M-band (4.7um). I complete Part 1 by outlining a future JWST survey that could enable the direct detection of sub-Jupiter mass exoplanets down to ice-giant size.

In Part 2, I present the state of the development of an emerging large-format deformable mirror technology for adaptive optics. The Netherlands Organization of Applied Scientific Research (TNO) recently developed a new style of high-efficiency hybrid-variable reluctance actuator that is the basis of an emerging large-format deformable mirror technology. I present my performance testing of this technology using two lab prototypes and compare my results against the needs for future ELT adaptive optics systems. I close Part 2 by reviewing the designs of five in progress adaptive secondary mirrors that incorporate the TNO technology for the NASA IRTF, UH-2.2m, Automated Planet Finder, the European Solar Telescope, and the W.M. Keck Observatory.

I conclude by sharing my perspectives on the near future of the field of exoplanet direct imaging. I add a final appendix in the form of a 10-minute science play, commemorating the experience of searching for direct imaging companions.