Information medium comprising two layers, method of manufacturing such an information medium, device for reading such an information medium

The present invention relates to an information medium comprising a first information layer (L1) and a second information layer (L2), said first and second information layers (L1, L2) comprising marks intended to store binary data, each mark being intended to be read by a light spot polarized according to a first direction (d1) or to a second direction (d2), wherein: the first information layer (L1) comprises first marks (101) sensitive to the first polarization direction, and second marks (102) not sensitive to said first polarization direction, said first and second marks being both not sensitive or equally sensitive to the second polarization direction, the second information layer (L2) comprising third marks (103) sensitive to the second polarization direction, and fourth marks (104) not sensitive to said second polarization direction, said third and fourth marks being both not sensitive or equally sensitive to the first polarization direction.