  Regular nanoscale perforations in graphene (graphene antidot lattices, GAL)
are known to lead to a gap in the energy spectrum, thereby paving a possible
way towards many applications. This theoretical prediction relies on a perfect
placement of identical perforations, a situation not likely to occur in the
laboratory. Here, we present a systematic study of the effects of disorder in
GALs. We consider both geometric and chemical disorder, and evaluate the
density-of-states as well as the optical conductivity of disordered GALs. The
theoretical method is based on an efficient algorithm for solving the
time-dependent Schr{\"o}dinger equation in a tight-binding representation of
the graphene sheet [S. Yuan et al., Phys. Rev. B 82, 115448 (2010)], which
allows us to consider GALs consisting of 6400 $\times$ 6400 carbon atoms. The
central conclusion for all kinds of disorder is that the gaps found for
pristine GALs do survive at a considerable amount of disorder, but disappear
for very strong disorder. Geometric disorder is more detrimental to gap
formation than chemical disorder. The optical conductivity shows a low-energy
tail below the pristine GAL band gap due to disorder-introduced transitions.
