Abstract: An illumination optical apparatus and a projection type display apparatus capable of preventing an image on boundary lines of a fly-eye lens from deviating from a designed position and preventing unevenness of brightness is provided: wherein a first lens holding member holding said first fly-eye lens; a second lens holding member joined to said first lens holding member, and holding said second fly-eye lens; and a third lens holding member joined to said second lens holding member, and holding an optical lens are provided; and said first lens holding member and said second lens holding member are joined to be relatively rotatable about an optical axis.

Abstract: An illumination optical apparatus and a projection type display apparatus capable of enhancing an illumination efficiency; having an ellipsoidal mirror, a light source arranged at a first focal point of the ellipsoidal mirror, a stop arranged closer to said light source side by a predetermined distance from a second focal point of said ellipsoidal mirror, and a positive refractive collimator lens for collimating a light flux emitted from the stop to a parallel light flux. A condition (0.01<L2/L1<0.06) is satisfied where, L1 is a distance from an apex of the ellipsoidal mirror to the second focal point thereof and, L2 (the light source side is a positive distance) is a distance from the second focal point of the ellipsoidal mirror to the stop.

Abstract: A projection type display apparatus, wherein a common case can be used for housing an illumination optical system even when a shape of an image display element and an optical path length in a prism are different, is provided: wherein a light source for emitting an illumination light, an image display device, an illumination optical system for irradiating the illumination light from the light source to the image display device, and a projection optical system for projecting an image formed by said image display device are provided; the illumination optical system comprises a first fly-eye lens and a second fly-eye lens arranged at each other's focal points, a first lens group and a second lens group arranged over a mirror for bending an optical path; the first and second lens groups have a same focal length but a different back focus; and predetermined condition formulas are satisfied.

Abstract: A projection type display apparatus, wherein a common case can be used for housing an illumination optical system even when a shape of an image display element and an optical path length in a prism are different, is provided: wherein a light source for emitting an illumination light, an image display device, an illumination optical system for irradiating the illumination light from the light source to the image display device, and a projection optical system for projecting an image formed by said image display device are provided; the illumination optical system comprises a first fly-eye lens and a second fly-eye lens arranged at each other's focal points, a first lens group and a second lens group arranged over a mirror for bending an optical path; the first and second lens groups have a same focal length but a different back focus; and predetermined condition formulas are satisfied.

Abstract: An illumination optical apparatus and a projection type display apparatus capable of preventing an image on boundary lines of a fly-eye lens from deviating from a designed position and preventing unevenness of brightness is provided: wherein a first lens holding member holding said first fly-eye lens; a second lens holding member joined to said first lens holding member, and holding said second fly-eye lens; and a third lens holding member joined to said second lens holding member, and holding an optical lens are provided; and said first lens holding member and said second lens holding member are joined to be relatively rotatable about an optical axis.

Abstract: An illumination optical apparatus and a projection type display apparatus capable of enhancing an illumination efficiency; having an ellipsoidal mirror, a light source arranged at a first focal point of the ellipsoidal mirror, a stop arranged closer to said light source side by a predetermined distance from a second focal point of said ellipsoidal mirror, and a positive refractive collimator lens for collimating a light flux emitted from the stop to a parallel light flux. A condition (0.01<L2/L1<0.06) is satisfied where, L1 is a distance from an apex of the ellipsoidal mirror to the second focal point thereof and, L2 (the light source side is a positive distance) is a distance from the second focal point of the ellipsoidal mirror to the stop.