David Doelman

PhD Student

Direct Imaging Using Liquid-Crystal Optics

Exoplanet -- High Contrast Imaging -- Aperture Masking -- Wavefront Sensing -- Coronagraphy

Current Research Summary:

With liquid-crystal technology it is possible to make arbitrarily-patterned diffractive phase plates that apply achromatic phase. In my work I look for uses of this technology to improve high-contrast imaging systems.

My main topic is the vector-Apodizing Phase Plate (vAPP) coronagraph, a single-optic pupil plane coronagraph. The achromatic properties of the liquid-crystal optics can be used to make broadband vAPP coronagraphs with up to 100% bandwidth. I designed and helped commission many vAPPs for the largest telescopes around the world (LBT, Magellan, Subaru, VLT, and ELT). I also work on improving the vector-vortex coronagraph to make it suitable for future space missions like HabEx.

In addition, I worked on wavefront sensing for non-common path aberrations. I upgraded the Zernike wavefront sensor to be able to measure phase and amplitude aberrations simultaneously. Furthermore, I designed vAPP coronagraphs to have additional holographic probes in the focal plane for wavefront sensing.

Lastly, I worked on improving sparse aperture masking by using holographic techniques to increase the throughput, number of baselines and number of closure phases. I designed a new mask, a holographic aperture mask (HAM), that is installed on Keck in OSIRIS.

Prior Research:

MSc at Leiden University

BSc at Leiden University