Dense Aperture Masking study : approaching theoretical contrasts with conventional, narrow-field Adaptive Optics


Fabien Patru, Julien Girard


European Southern Observatory (ESO)


We present an alternative concept of high-contrast imager for early science with the ELTs. Based on the densified pupil concept introduced by A. Labeyrie for diluted telescope arrays, it is applied here on a segmented mirror telescope turned into a direct imaging fizeau combiner. Our simulations show that an AO system already available today coupled with a simple Dense Aperture Mask (DAM) can produce a PSF close to the theoretical one and more robust to wavefront residual errors in terms or contrast and stability. A demonstrator for VLT/NACO and VLT/SPHERE is studied, including strehl ratios, contrasts and inner-working angles gains using enhancing methods such as ADI/LOCI processing. The spatial sampling of DAM improves significantly the strehl of the diffraction limited PSF for a given set of atmospheric conditions and AO performances. It can be extended to the E-ELT with a simple single-conjugate adaptive optics (first light instrument) or an extreme AO instrument like E-ELT/EPICS.

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