We define a new class of binary matrices by maximizing the peak-sidelobe
distances in the aperiodic autocorrelations. These matrices can be used as
robust position marks for in-plane spatial alignment. The optimal square
matrices of dimensions up to 7 by 7 and optimal diagonally-symmetric matrices
of 8 by 8 and 9 by 9 were found by exhaustive searches.Comment: 8 pages, 6 figures and 1 tabl