Color separation optical system and image projection apparatus

摘要

A color separation optical system is disclosed which is effective in improving black color and black unevenness. Linearly polarized light impinging on a dichroic surface at an incident angle smaller than 45 degrees and then impinging on a polarization beam splitting surface at an incident angle larger than 45 degrees is referred to as first incident-angle light. A wavelength which is longer than a wavelength at the maximum transmittance of the dichroic surface for the first incident-angle light and at which the transmittance of the dichroic surface for the first incident-angle light is 10% is referred to as Wa, and a wavelength range shorter than Wa is referred to as W. The polarization beam splitting surface has a characteristic in which its transmittance for the first incident-angle light in the wavelength range W is 5% or lower.