US Patent 7416307 Optical apparatus and projection apparatus

An optical apparatus provided with a light combining prism having three light incident faces, receiving the three beams of light having different wavelength bands through the three light incident faces, and combining the three incident beams of light for output, three reflection type polarization plates, three plate-like reflection type polarization elements provided corresponding to the three reflection type liquid crystal panels, each receiving a different wavelength band of light among the three different wavelength bands, each selecting a first polarized beam component to pass and making it strike the corresponding reflection type liquid crystal panel by two perpendicular polarized beam components, and each making modulated light spatially modulated and converted to a second polarized beam component at the reflection type liquid crystal panel strike the corresponding incident face among the three light incident faces of the combining prism, and at least three fixing plates with surfaces which can be joined with the three light incident faces of the light combining prism, wherein at least the reflection type polarization elements between the reflection type polarization elements and reflection type liquid crystal panels are fixed to the corresponding light incident faces of the light combining prism via the fixing plates, and a projection apparatus using the same.