Arrangement of .lambda./2 retardation plate in projector

DETAILED DESCRIPTION An object of the present invention is thus to provide a technique for reducing chrominance nonuniformities in the images displayed by a projector.
At least part of the above and other objects of the present invention is attained by a projector for projecting and displaying a color image.
The first projector comprises: an illuminating optical system that emits illuminating light; a color-separating optical system that separates the illuminating light emitted from the illuminating optical system into a first through third beam of colored light, each of which has one of three color components; first through third electro-optical devices that modulate the first through third beams of colored light separated by the color-separating optical system according to image information to form a first through third beam of modulated light; a color combiner that combines the first through third beams of modulated light by reflecting the first and third beams of modulated light while transmitting the second beam of modulated light; a projecting optical system that projects the composite light emitted from the color combiner; and a .
lambda.
/2 retardation plate provided on at least one of an incident side and an exit side of both of the first and third electro-optical devices, the .
lambda.
/2 retardation plate having a first surface open to the atmosphere and a second surface in contact with a transmissive member.
Since the .
lambda.
/2 retardation plate is provided with one surface open to the atmosphere and its other surface in contact with a transmissive member, the distortion of the .
lambda.
/2 retardation plate is reduced, and the chrominance nonuniformities in the images displayed are reduced accordingly.
In a preferred embodiment of the invention, a direction of polarization of the first and third beams of modulated light incident on the color combiner is a first direction of polarization, while a direction of polarization of the second beam of modulated light is a second direction of polarization perpendicular to the first direction