| dc.description.abstract | The angular resolution of an imaging system is sharply bounded by the diffraction
limit, a fundamental property of electromagnetic radiation propagation. In order
to increase resolution and see finer details of remote objects, the sizes of telescopes
and cameras must be increased. As the size of the optics increase, practical problems
and costs increase rapidly, making sparse aperture systems attractive for some
cases. The method of Intensity Correlation Imaging (ICI) provides an alternative
method of achieving high angular resolution that allows a system to be built with
less stringent precision requirements, trading the mechanical complexity of a typical
sparse aperture for increased computational requirements. Development of ICI has
stagnated in the past due to the inadequacies of computational capabilities, but the
continued development of computer technologies now allow us to approach the image
reconstruction process in a new, more e ffctive manner. This thesis uses estimation
methodology and the concept of transverse phase diversity to explore the modern
bounds on the uses of ICI.
Considering astronomical observations, the work moves beyond the traditional,
single-parameter uses of ICI, and studies systems with many parameters and complex
interactions. It is shown that ICI could allow significant new understanding of complex
multi-star systems. Also considered are exoplanet and star-spot measurements;
these are less promising due to noise considerations.
Looking at the Earth imaging problem, we find significant challenges, particularly related to pointing requirements and the need for a large field-of-view. However,
applying transverse phase diversity (TPD) measurements and a least-squares estimation
methodology solves many of these problems and re-opens the possibility of
applying ICI to the Earth-imaging problem. The thesis presents the TPD concept,
demonstrates a sample design that takes advantage of the new development, and
implements reconstruction techniques. While computational challenges remain, the
concept is shown to be viable.
Ultimately the work presented demonstrates that modern developments greatly
enhance the potential of ICI. However, challenges remain, particularly those related
to noise levels. | en |
