Patent ID: 8128233

Claim:
An illuminating optical system for a projector including a light source and a plurality of display panels, said illuminating optical system comprising: a first integrator that includes a plurality of lens cells that divide a luminous flux emitted by the light source into a plurality of partial luminous fluxes and that condense the respective partial luminous fluxes; a second integrator that includes a plurality of lens cells on which the respective partial luminous fluxes are incident; a polarization converting element that uniformizes polarizing directions of the luminous fluxes having passed through the respective lens cells of said second integrator; and a color separating unit that separates each of the luminous fluxes from said polarization converting element into a plurality of color lights of different wavelengths, wherein a field lens and a condenser fens are arranged between said polarization converting element and said color separating unit, wherein said field lens superimposes, on said plurality of display panels, the luminous fluxes that have passed through the respective lens cells of said first integrator, wherein said condenser lens is located closer to said color separating unit, and wherein a distance between said condenser lens and said field lens is equal to a synthesized focal distance provided in an optical unit including condenser lens and said field lens.