Wavelength-selective polarization conversion element, illumination optical system, projection display optical system, and image projection apparatus

摘要

A wavelength-selective polarization conversion element is disclosed which has a polarization conversion function that has been obtained by a polarization conversion element and a wavelength-selective phase plate in the past. The element includes a polarization beam splitting film and a phase plate. The film splits light and has a characteristic in which the transmittance for light with a first polarization direction and the transmittance for light with a second polarization direction are changed between a value higher than 50% and a value lower than 50% depending on wavelength region. The phase plate changes the polarization direction of light transmitted or reflected by the film between the first and second polarization directions. The element converts light in two of the first to third wavelength regions into polarized light with one polarization direction and converts light in the other wavelength region into polarized light with another polarization direction.