We present the monochromatic lab verification of the newly developed SCAR coronagraph that combines a phase plate (PP) in the pupil with a microlens-fed single-mode fiber array in the focal plane. The two SCAR designs that have been measured, create respectively a 360 degree and 180 degree dark region from 0.8-2.4 \lambda/D around the star. The 360 SCAR has been designed for a clear aperture and the 180 SCAR has been designed for a realistic aperture with central obscuration and spiders. The 360 SCAR creates a measured stellar null of 2−3×10−4 , and the 180 SCAR reaches a null of 1×10−4 . Their monochromatic contrast is maintained within a range of ± 0.16 \lambda/D peak-to-valley tip-tilt, which shows the robustness against tip-tilt errors. The small inner working angle and tip-tilt stability makes the SCAR coronagraph a very promising technique for an upgrade of current high-contrast instruments to characterize and detect exoplanets in the solar neighborhood.
@article{arxiv.1803.10693,
title = {The Single-mode Complex Amplitude Refinement (SCAR) coronagraph: II. Lab verification, and toward the characterization of Proxima b},
author = {S. Y. Haffert and E. H. Por and C. U. Keller and M. A. Kenworthy and D. S. Doelman and F. Snik and M. J. Escuti},
journal= {arXiv preprint arXiv:1803.10693},
year = {2018}
}