ABSTRACT We present an analytical description of the diffraction halo created by optical aberrations randomly distributed over hexagonal segments of a segmented mirror. We do not restrict ourselves to the piston and tip-tilt errors only, but show that the halo from any type of the aberration can be described in a general form. We also study the ability of the high order adaptive optics to correct for this type of aberrations. These effects are especially critical for application of the high contrast im aging with extremely large segmented telescopes. Keywords : ELT, segmentation, speckles, adaptive optics 1. INTRODUCTION The halo created by the segmentati on of the primary mirror in an extremely large segmented telescope 1 is the important component the point spread function (PSF) which characterizes the performance of an ELT as an imaging device. Although the halo has been analyzed in a number of publications, the theoretical study has been limited so far to the piston and tip-tilt aberrations only,