In practice, the image of star never appears as a single point on a detector; rather, a diffraction pattern appears. Although a larger diameter telescope reduces the size of the diffracted spot, the starlight is always spread throughput the image, even in a perfect system. Exoplanets reside very near to the star and, therefore, are often buried within the diffracted starlight and its associated noise.
Astronomers remove the starlight from the image in order to isolate the planet light. This can be done in two ways: by subtracting the image of the star in post-processing and/or removing the light from the star optically. A coronagraph is an optical instrument that makes this possible through exquisite wavefront control.
I strive to improve the optical design of coronagraphs for extremely high contrast exoplanet imaging at small angular separation from a star and develop optimal wavefront control algorithms.Download PDF Download PDF Download PDF