Patent attributes
A polarizing beam splitter having a film made of a high-refractivity material and a film made of a low-refractivity material alternately stacked on a substrate. When an incidence angle with respect to a film surface in a particular wavelength is set as θ (°), the following conditional expressions are satisfied in the range of 40≦θ≦50(°):0.99≦Rs(45)/Rs(θ)≦1.04, 0.96≦Tp(45)/Tp(θ)≦1.05, where Rs(θ): reflectivity of polarized light s at a θ incidence; Tp(θ) transmissivity of polarized light p at a θ incidence angle; Rs(45): reflectivity of polarized light s at a 45° incidence angle; and, Tp(45) transmissivity of polarized light p at a 45° incidence angle. The transmissivity of the polarized light p does not decrease and the reflectivity of the polarized light s is nearly 100% with respect to even a broad angle region.
