Polarizer, polarization light source and image display unit using them

A polarization component comprising at least two reflective polarizer layers and a retardation layer disposed between the reflective polarizer layers, wherein

• the two reflective polarizer layers are reflective circular polarizer layers that selectively transmit one of clockwise circularly polarized light or counterclockwise circularly polarized light while selectively reflecting the other, wherein
• the two reflective circular polarizer layers have selective reflection wavelength bands for selective reflection of polarized light, the bands overlapping each other at least partially, and
• the retardation layer satisfies conditions of Formulae (I) and (II) below:
• R≦λ/10 (I)
• R≧λ/8 (II)
• wherein in Formulae (I) and (II), λ denotes a wavelength of light entering the retardation layer;
• R denotes an absolute value of retardation of an in-plane retardation in a X-axis direction and in a Y-axis direction with respect to incident light from a Z-axis direction (normal direction), where the X-axis direction is a direction showing a maximum refractive index within the plane of the retardation layer (in-plane slow axis direction), the Y-axis direction is a direction perpendicular to the X-axis direction within the plane of the retardation layer (in-plane fast axis direction), and the Z-axis direction is a thickness direction of the retardation layer and perpendicular to the X-axis direction and the Y-axis direction;
• R′ denotes an absolute value of retardation between a X′-axis direction and a Y′-axis direction with respect to incident light from a direction inclined by at least 30° with respect to the Z-axis direction, where the X′-axis direction is an axial direction within a plane of the retardation layer perpendicular to the incidence direction of the incident light inclined by at least 30° with respect to the Z-axis direction, and the Y′-axis direction is a direction perpendicular to the incidence direction and to the X′-axis direction.