Patent ID: 7538944

Claim:
A polarizing filter of planar transparent substrate plates with a polarization separating filter layer to transmit or reflect incident light according to direction of polarization, said polarizing filter having a plane of incidence and a plane of transmission in the direction of two orthogonal X- and Y-axes and a thickness in the direction of Z-axis orthogonal to said X- and Y-axes, characterized in that said polarizing filter comprises: a polarization separating filter layer comprising a first group of inclined filter layer sections each having a plane in the direction of said Z- and Y-axes inclined in the direction of said X-axis through a predetermined angle, alternately with a second group of inclined filter layer sections each having a plane in the direction of said Z- and Y-axes inclined through the same angle as but in a symmetrically inverse direction relative to said inclined filter layer sections of the first group; the inclined filter layer sections of the first group being connected crosswise with said inclined filter layer sections of the second group in a cross shape or in a T-shape at positions inward of said plane of incidence and the plane of transmission of said polarizing filter; and each one of said inclined filter layer sections of the first and second groups, which is exposed on said plane of incidence and said plane of transmission of said polarizing filter at opposite ends, being connected crosswise with an adjacent inclined filter layer section of the other group in a cross shape or in a T-shape at least at two positions; each one of said inclined filter layer sections of the first and second groups, which is exposed on said plane of incidence or on said plane of transmission of said polarizing filter at one end alone, being connected crosswise with an inclined filter layer section of the other group in a T-shape at the other end; and each one of said inclined filter layer sections of the first and second groups, which is not exposed on said plane of incidence and said plane of transmission of said polarizing filter at any end, being connected crosswise with inclined filter layer sections of the other group in a T-shape at opposite ends.