To provide an illumination optical system capable of yielding uniform intensity distribution, and also reducing the loss of light quantity so as to yield illumination improved in the efficiency of using light, and a projection type display device.
The illumination optical system 100 is equipped with: a light source device 110 emitting non-polarized light; a first lens array 120 dividing light emitted from the light source device into a plurality of partial luminous fluxes and emitting the partial luminous fluxes; a second lens array 30 collimating the plurality of partial luminous fluxes emitted from the first lens array and emitting them; a polarized light changing element 140 changing the plurality of partial luminous fluxes collimated and emitted from the second lens array 130 to a kind of linearly polarized light beams having a uniform polarization direction respectively and emitting them; and a third lens array 150 diverging the plurality of linearly polarized light beams emitted from the polarized light changing element and emitting them, and illuminates the light incident surface of a liquid crystal light valve 400 functioning as an optical device as an illuminating area. The illumination optical system 100 is preferably used for the projection type display device which projects and displays an image.
Osamu Suzawa
Kazuhiko Miyasaka
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