Hi, everyone! I am a third-year graduate student and research assistant at IfA Hilo working with Mark Chun and Christoph Baranec. My current research project is helping to commission Robo-AO-2, and use it to perform hybrid AO demonstration at UH88. I worked with Mark Chun on using deflectometry for large convex mirror metrology for my 699-1 and ultracool dwarfs classification with Mike Liu for my 699-2. Before coming to graduate school, I received my Bachelor’s degree in Physics from Illinois Wesleyan University in the summer of 2020. My undergraduate research was building a Fourier Transform spectrometer with a novel design to study cosmic analog dust. Outside of school, I love anything nature related such as hiking and swimming. I also enjoy dancing 😉


Ph.D. Topic

Topic: HAPA: Hybrid Atmospheric Phase Analysis A Wavefront Sensing Technique for Improving the Adaptive Optics Correction of Fainter Stars
Committee: Christoph Baranec(Chair), Mark Chun, Richard Dekany (Caltech), Michael Liu, Peter Sadowski (Dept. of Information and Computer Sciences)

Direct imaging of exoplanets allows us to measure positions and chemical signatures of exoplanets. However, it is difficult from the ground because it requires an adaptive optics system to provide an extremely well corrected wavefront to enable coronographic techniques. Currently only natural guide star AO systems have demonstrated the necessary wavefront correction for direct imaging of exoplanets. However, using a stellar source as the guide star for wavefront sensing limits the number of exoplanet systems we can directly image because it requires a relatively bright V~10 mag star. To increase the number of observable targets, we need to push the limit of guide stars to fainter magnitudes for high Strehl ratio correction. We propose to use Hybrid Atmospheric Phase Analysis (HAPA), that combines laser wavefront sensing with stellar wavefront sensing to achieve the high Strehl correction with fainter natural guide stars. My dissertation will focus on demonstrating this approach using Robo-AO-2 at the UH 2.2m telescope on Maunakea. The dissertation consists of 3 projects. Firstly, we will commission Robo-AO-2. Secondly, I will run simulations for HAPA on small and large aperture telescopes and demonstrate it on-sky with Robo-AO-2. Lastly, I will work with adaptive secondary mirrors in development. I will gain expert knowledge and skills with adaptive optics systems over the duration of my dissertation.

Ruihan (Suzanne) Zhang

Graduate Student
B.S. 2020, Illinois Wesleyan University
  • Instrumentation, Adaptive Optics
IfA Hawaii island, 133