Deep nulling of laser light in a rotational shearing interferometer

There is great interest in techniques that potentially enable the direct detection of light from planets orbiting nearby stars. In one technique, nulling interferometry, the light from two or more separate telescopes can be destructively interfered to cancel the light from the star, allowing detection of the faint off-axis light from an orbiting planet or circumstellar disc. At the Jet Propulsion Laboratory, broadband white light nulls limited by dispersion effects have been previously reported. In this paper, we investigate other limiting effects using a monochromatic laser source. We report transient laser nulls as deep as 1 part in 106 at a wavelength of 633 nm in a nulling interferometer operated in air. We discuss the techniques used to obtain these nulls and the residual sources of stray light and other null limitations.