OPTICAL UNIT AND PROJECTION TYPE IMAGE DISPLAY UNIT USING IT

摘要

An optical unit which separates a light from a light source into a plurality of chromatic lights by a color separating means to allow them to enter respective associated reflection-type image display elements, forms an optical image for each chromatic light by using polarization characteristics provided by a reflection-type image display element and according to an image signal, synthesizes chromatic light-based optical images by a color synthesizing means, and magnifies and projects the synthesized image by a projection lens, characterized in that a reflection-type polarization plate that acts as a polarization plate by diffraction is disposed, as a polarizer and an analyzer with respect to reflection-type image display elements, on an optical path extending from the color separating means to the reflection-type image display elements, an optical chassis that holds the reflection-type polarization plate and the reflection-type image display elements, has a translucent window on the incident light side of the reflection-type polarization plate, and is sealed on the outgoing light side of the reflection-type polarization plate by the incident surface of the color synthesizing means is provided, an sealed space is formed by the optical chassis, the reflection-type image display elements, and the incident surface of the color synthesizing means, and a translucent fluid having a refractive index of 1.2 to 1.9 is disposed in the sealed space.