Reduction of the diffraction pattern in segmented apertures

New discoveries in astronomy require the use of ever larger telescope. These telescopes require segmented apertures, since current technology does not provide for the fabrication of monolithic mirrors with diameters much larger than 8 m. As a result, the point spread function (PSF) of the system presents a diffraction pattern characteristic of the segmentation geometry, and this complicates the task of detecting faint structures with high spatial resolution. In this work, we investigate the use of amplitude filters at the pupil plane to decrease the intensity of this diffraction pattern. It is sufficient if this diffraction pattern is reduced below the residual halo that remains after adaptive optics compensation, so that the intensity distribution that surrounds the PSF core is limited by scattering rather than diffraction. We show different kinds of filters that allow us to achieve this goal. We analyze their performance, taking into account some unavoidable errors in the telescope operation such as imperfect phasing of the telescope segments and gaps between them. Finally, we discuss the application of the technique considering errors in the adaptive optics correction.