Interferometric wavefront sensors for high contrast imaging

Several novel interferometer configurations are presented which have a high signal-to-noise ratio making them suitable for high contrast imaging. High contrast imaging instruments, such as required to directly observe extrasolar planets, will require adaptive optics systems capable of reducing the atmospherically induced phase aberrations to a few nm of wave-front error. The interferometer designs presented are shown to provide a higher contrast and/or are more robust than the conventional Mach-Zehnder interferometer, which has previously been considered for high contrast imaging. In addition, all of the interferometric-based wave-front sensors are shown to provide a significant improvement in the achievable contrast ratio when compared with conventional adaptive optics systems containing Shack-Hartmann wave-front sensors.