| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element capable of forming a surface light source device, which hardly cause degradation of performance of damage to a shape due to adhesion to adjacent members, has excellent workability is handling and emits light with excellent forward directivity, and an LCD device excellent luminance. SOLUTION: The optical element comprises cholesteric liquid crystal layers (1, 2) with Grandjean orientation which are mutually laminated, in combination of the selective reflection wavelength regions of circularly polarized light common to each other and with the left- or right-handed polarization of the circularly polarized light reversed by the selective reflection, or in combination of the selective reflection wavelength regions common to each other and with the left- or right-handed polarization of the circularly polarized light unchanged by the selective reflection via a half-wave plate. The surface light source device comprises the optical element arranged on a sidelight type or a direct lower type surface light source provided with a fluorescent lamp composed of a tube with three wavelengths as a light source. The optical element forms the LCD device. In the optical element and the devices, the light in a specified wavelength region transmitting through the first cholesteric liquid crystal layer is selectively reflected and shielded by the second cholesteric liquid crystal layer.
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