To provide a polarized beam splitter which causes little changes in the reflectance or the transmittance of P-polarized light and S-polarized light even when the incident angle of a beam incident on the film plane changes.
The polarized beam splitter 10 has a dielectric multilayer film 3 produced by alternately depositing high refractive index dielectric films consisting of a high refractive index substance and low refractive index dielectric films consisting of a low refractive index substance on the slope face of a right-angle prism 1 as a substrate, and it is characterized in that the optical film thickness of each layer is specified to, from the substrate side with respect to the designed wavelength λ, (0.4 to 0.6)×λ/4 for the first layer, (0.6 to 0.8)×λ/4 for the second layer, [(0.9 to 1.1)×λ/4 (0.5 to 0.8)×λ/4] q (wherein q≥1) for from the third layer to the (2q+2)th layer, (0.9 to 1.1)×λ/4 for the (2q+3)th layer, (0.6 to 0.8)×λ/4 for the (2q+4)th layer, and (0.4 to 0.6)×λ/4 for the (2q+5)th layer.
UZAWA KUNIHIKO
KAWAMATA TAKESHI
TOYOHARA NOBUYOSHI
DEGUCHI TAKESHI
Next Patent: POLARIZED LIGHT SEPARATION FILM AND POLARIZED LIGHT SEPARATION PRISM