Patent ID: 7289267

Claim:
A polarizing beam splitter comprising: a substrate; and, a multilayer structure having: a film made of a high-refractivity material; and, a film made of a low-refractivity material, the film made of a high-refractivity material and the film made of the low-refractivity material being alternately stacked on the substrate, the multilayer structure satisfying the following conditional expressions 1A, 1B, and 1C are satisfied in an entire range of 40≦θ≦50 (°) when an incidence angle with respect to a film surface in a particular wavelength is θ (°): 0.99 ≦Rs (45) /Rs (θ)≦1.04 1A 0.96 ≦Tp (45) /Tp (θ)≦1.05 1B Tp >90.00% 1C where, Rs(θ): reflectivity of polarized light s at an incidence angle of θ; Tp(θ): transmissivity of polarized light p at an incidence angle of θ; Rs (45): reflectivity of polarized light s at the incidence angle of 45°; and, Tp(45): transmissivity of polarized light p at the incidence angle of 45°.