Polarized beam splitter and an illumination optical system and a projector provided with a polarized beam splitter

摘要

A beam splitter for use in a projector is provided with a first transparent base; a second transparent base; and a polarizing multilayered film placed between the first and second transparent bases. The polarizing multilayered film includes high refraction layers each having a refractive index n.sub.H and low refraction layers each having a refractive index n.sub.L lower than the refractive index n.sub.H the high refraction layers and the low refraction layers being alternately laminated one another. The refractive index n.sub.H and the refractive index n.sub.L satisfies the following equation: ##EQU1##