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Achromatic Four Quadrant Phase Mask Coronagraph using the Dispersion of Form Birefringence
Published online by Cambridge University Press: 28 May 2003
Abstract
We describe an alternative design for the 4-quadrant phase mask coronagraph described recently by Rouan et al. (2000). Based on the same principle, i.e. producing a very efficient nulling by mutually destructive interferences of the coherent light from the main source, our mask realises the π phase shift using some properties of ZOGs (Zeroth Order Gratings) and according to an original scheme respecting the 4-quadrant symmetry. When the period of the one-dimension grating structure is smaller than the wavelength of the incident light, the structure becomes birefringent. The effective refractive indices depend on the wavelength. Using this feature, we can design a mask whose nulling efficiency is maintained within a wide wavelength range. Numerical simulations were made according to the RCWA (Rigorous Coupled Wave Analyses).
- Type
- Research Article
- Information
- European Astronomical Society Publications Series , Volume 8: Astronomy with High Contrast Imaging , 2003 , pp. 117 - 128
- Copyright
- © EAS, EDP Sciences, 2003
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