Extinction controlled adaptive mask coronagraph Lyot and phase mask dual concept for wide extinction area

摘要

A dual coronagraph based on the Adaptive Mask concept is presented in this paper. ALyot coronagraph with a variablediameter occulting disk anda nulling stellar coronagraph based on the Adaptive Phase Mask concept using polarizationinterferometry are presented in this work. Observations on sky and numerical simulations show the usefulness of theproposed method to optimize the nulling efficiency of the coronagraphs. In the case of the phase mask, the active controlsystem will correct for the detrimental effects of image instabilities on the destructive interference (low-order aberrationssuch as tip-tilt and focus). The phase mask adaptability both in size, phase and amplitude also compensate formanufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used toprovide variable transmission of an annulus around the phase mask, but also to achieve the achromatic π phase shift inthe core of the PSF by rotating the polarization by 180°.A compressed mercury (Hg) drop is used as an occulting disk forthe Lyot mask, its size control offers an adaptation to the seeing conditions and provides an optimization of the Tip-tiltcorrection.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.