Article

A Coronagraph Using A Liquid Crystal Array And A Deformable Mirror For Active Apodizing And Phase Corrections

Almost all high-contrast imaging coronagraphs proposed until now are based on passive coronagraph optical components. That is, the coronagraph cannot be actively controlled to be optimized for best performance. Pupil apodizing, which modifies the light transmission on the pupil, is one of the promising techniques for high-contrast imaging. Here, we propose, for the first time, a high-contrast imaging coronagraph that integrates a liquid crystal array for active pupil apodizing and a deformable mirror for active phase correction. In such a way, source errors such as the initial transmission error and wavefront error can be actively and efficiently compensated based on an optimized algorithm, which is optimized for maximum contrast in the discovery area. In addition, the use of a liquid crystal array makes this system more flexible and able to create any apodizing pupil, including square or circle aperture with or without central obstruction. In this article, we discuss the working principle and estimated performance of the coronagraph. We also demonstrate that the chromatic aberration induced by a liquid crystal array is sufficiently small, which makes it suitable to be used for ground-based near-infrared coronagraphic Extreme-AO systems.

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