To quantify development of sub-micron structural anisotropy in the cooling die, we analysed a series of images taken with optical microscopy at multiple positions in the cooling die, namely 3 cm and 21 cm (Fig. ). Each image series consists of six images taken at equally spaced positions along the path from the skin to the core of the sample (Fig. ). Positions near the skin show a bimodal distribution, with one distribution of a higher mean WOP around 0.4 and one of WOP around 0 (Fig. ). The positions near the core show only mean WOP values around 0. Whereas the sample measured with a distance of 21cm stays bimodal at relative positions of 3 and above, the samples measured at a 3 cm distance show a largely monomodal distribution for position 4 and below with WOP values around 0. Thus, the sample at 3 cm is anisotropic only near the skin whereas the sample at 21cm shows a wider anisotropic region. Additional data for measurement distances of 9 cm and 15 cm along the cooling die can be found in Fig. . Generally, the images taken closer to the skin show higher average sub-micron anisotropy and the size of the anisotropic region increases with increasing distances within the cooling die.