Influence of the Al₂O₃ layer on coronagraphic performance of the GMT for a 6th-order PC in I-band. These data show the difference between the case with and without segment variations. Here n is the exponent of the PSD used to generate the distribution of Al₂O₃ on the primary mirror. We observe that the coronagraphic residuals generally increase with decreasing n, but do not exceed 10^–9 contrast.