Coronagraphy

Coronagraphs are optical devices designed to allow the observation of faint sources close to a bight object (usually the Sun or any other star). Coronagraphs are essential tools to enable direct imaging of exoplanets (planets around stars other than the Sun). I have been working with other astronomers and engineers to develop high performance coronagraphs for use on ground and space telescopes to image and characterize planetary systems around nearby stars.

Introduction to coronagraphy
Overview of coronagraphy, coronagraph designs.

Phase-Induced Amplitude Apodization (PIAA) coronagraphy
This coronagraph offers high efficiency and performance. I have been working since 2003 with other scientists & engineers on this concept both on "paper" and in laboratory experiments.
Collaborators: NASA Ames Coronagraph Experiment (ACE), NASA JPL High Contrast Imaging Testbed (HCIT), PECO team, Subaru Coronagraphic Extreme-AO (SCExAO) team
PIAA Complex Mask Coronagraph [draft paper (pdf)]

Polychromatic focal plane masks for coronagraphs
[draft paper (pdf)]
Collaborators: Frantz Martinache, Ruslan Belikov, NASA Ames/NASA JPL coronagraphy groups The focal plane mask in high performance coronagraphs is often difficult to manufacture for polychromatic use. A possible solution is to use a properly designed diffraction grating as a focal plane mask.

Coronagraphic Astrometry
(This is not really coronagraphy, but it would be a great complement to a space coronagraph)
A technique to obtain high precision astrometric measurement (position of the central star) with a coronagraphic telescope is discussed.

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