“…In the past years the moire´fringes formed by overlapping simple structures such as line, radial, and circular gratings have been widely examined [4][5][6][7][8]. Also, complicated types of gratings such as Fresnel zones, skewed radial lines, spiral lines, matched radial-parallel lines and elongated circles have been studied for specific applications in moire´metrology [9][10][11][12][13][14]. If any two gratings are superimposed onto each other, optical moire´s readily appear even under the illumination of a white light source.…”