cross section through a post with the lc distorted around it from one corner to the diagonally opposite one this alignment around the post then tends to seed the alignment of the lc above the post such that the average orientation is also along that diagonal by tilting the posts along one of the diagonals fig2 it is possible to favour that alignment direction through computer simulation of this geometry we found that although there is only one azimuthal alignment direction there are in fact two states with similar energies but which differ in how much the lc tilts fig2 is a schematic of the two states in one state shown on the left of fig2 the lc is highly tilted and in the other it is planar around the posts the exact nature of the lc orientation depends on the details of the structure but for a range of parameters there are two distinct states with different tilts the two states may be distinguished by viewing through a polariser 8 and an analyser 6 the low tilt state has high birefringence and the high tilt state has low birefringence without limiting the scope of the invention in any way we think that the two states may arise because of the way in which the lc is deformed by the post flowing around a post causes regions of high energy density at the leading and trailing edges of the post where there is a sharp change in direction this can be seen in fig1 at the bottom left and top right corners of the post this energy density is reduced if the lc molecules are tilted because there is a less severe direction change this is clear in the limit of the molecules being homeotropic.