Calibrating an Interferometric Null

One of the biggest challenges associated with a nulling interferometer-basedapproach to detecting extra-solar Earth-like planets comes from the extremelystringent requirements of pathlength, polarization and amplitude matching inthe interferometer. To the extent that the light from multiple apertures arenot matched in these properties, light will leak through the nuller and confusethe search for a planetary signal. Here we explore the possibility of using thecoherence properties of the starlight to separate contributions from the planetand nuller leakage. We find that straightforward modifications to the opticallayout of a nulling interferometer will allow one to measure and correct forthe leakage to a high degree of precision. This nulling calibration relaxes thefield matching requirements substantially, and should consequently simplify theinstrument design.Comment: 24 Pages, accepted for publication in Ap