Abstract: A projection optical system for projecting, while enlarging, an image formed on an image formation surface onto an image projection surface from an oblique direction relative thereto has at least three optically powered reflective surfaces and a refractive lens surface having a non-rotation-symmetric free-form curved surface and disposed between the first and second reflective surfaces as counted from the image formation surface side.

Abstract: A projection type image display apparatus has: an illumination optical system generating illumination light; a projection optical system projecting an image light onto a screen; a digital micromirror device (DMD) modulating the illumination light so as to form the image light; and a reflection mirror arranged in a position opposite to an optical path of the illumination light entering the DMD. The reflection mirror reflects an off-light reflected by the DMD in an “OFF” state in a direction separated from a projection light reflected by the DMD in an “ON” state.

Abstract: In a projection optical system for obliquely performing enlargement projection of an image formed on a display device surface onto a screen surface, a plurality of reflective surfaces are provided, at least one of which is a curved reflective surface having an optical power. Letting the curved reflective surface, out of said at least one curved reflective surface, having the largest effective optical region be the largest curved reflective surface, the reflective surface other than the largest curved reflective surface is slightly decentered with the largest curved reflective surface kept in a fixed state so as to perform pixel shift on the screen surface in a vertical direction, or a horizontal direction, or an oblique direction, or vertical and horizontal directions within the range of a pixel pitch.

Abstract: A projection optical system for projecting, while enlarging, an image formed on an image formation surface onto an image projection surface from an oblique direction relative thereto has at least three optically powered reflective surfaces and a refractive lens surface having a non-rotation-symmetric free-form curved surface and disposed between the first and second reflective surfaces as counted from the image formation surface side.

Abstract: A projection optical system for projecting, while enlarging, an image formed on an image formation surface onto an image projection surface from an oblique direction relative thereto has at least three optically powered reflective surfaces and a refractive lens surface having a non-rotation-symmetric free-form curved surface and disposed between the first and second reflective surfaces as counted from the image formation surface side.

Abstract: A projection type image display apparatus has: an illumination optical system generating illumination light; a projection optical system projecting an image light onto a screen; a digital micromirror device (DMD) modulating the illumination light so as to form the image light; and a reflection mirror arranged in a position opposite to an optical path of the illumination light entering the DMD. The reflection mirror reflects an off-light reflected by the DMD in an “OFF” state in a direction separated from a projection light reflected by the DMD in an “ON” state.

Abstract: A projection optical system for projecting, while enlarging, an image formed on an image formation surface onto an image projection surface from an oblique direction relative thereto has at least three optically powered reflective surfaces and a refractive lens surface having a non-rotation-symmetric free-form curved surface and disposed between the first and second reflective surfaces as counted from the image formation surface side.

Abstract: In a projection optical system for obliquely performing enlargement projection of an image formed on a display device surface onto a screen surface, a plurality of reflective surfaces are provided, at least one of which is a curved reflective surface having an optical power. Letting the curved reflective surface, out of said at least one curved reflective surface, having the largest effective optical region be the largest curved reflective surface, the reflective surface other than the largest curved reflective surface is slightly decentered with the largest curved reflective surface kept in a fixed state so as to perform pixel shift on the screen surface in a vertical direction, or a horizontal direction, or an oblique direction, or vertical and horizontal directions within the range of a pixel pitch.

Abstract: A projection optical system includes from the enlargement side a first lens unit, a mirror which is an optical path bending member, a second lens unit, and a third lens unit. The projection optical system is designed so that a condition (1), 5.5<T12/FL<12.0, is fulfilled. Here, T12 is the air equivalent distance between the first lens unit and the second lens unit, and FL is the overall focal length of the projection optical system. By fulfilling the condition (1), it is unnecessary that the diameter of the first lens unit be extremely large. It is also unnecessary to change the lens shape to prevent interference between the first lens unit and the second lens units, so that an increase in the cost of the projection optical system can be suppressed.

Abstract: A projection optical system includes from the enlargement side a first lens unit, a mirror which is an optical path bending member, a second lens unit, and a third lens unit. The projection optical system is designed so that a condition (1), 5.5<T12/FL<12.0, is fulfilled. Here, T12 is the air equivalent distance between the first lens unit and the second lens unit, and FL is the overall focal length of the projection optical system. By fulfilling the condition (1), it is unnecessary that the diameter of the first lens unit be extremely large. It is also unnecessary to change the lens shape to prevent interference between the first lens unit and the second lens units, so that an increase in the cost of the projection optical system can be suppressed.

Abstract: A projection optical system has three LCLVs; a first color-separating mirror for separating a substantially polarized light into a first and second color lights and a third color light; a half-wave plate for rotating the polarization direction of either one(s) of the separated light; a second color-separating mirror for synthesizing the first and the third color light, and further, separating the second color light; a first PBS for separating the first and third color lights and illuminating the first and third LCLVs, respectively, and synthesizing image lights from the first and third LCLVs; a second PBS for illuminating the second LCLV and emitting a image light modulated by the second LCLV; a half-wave plate disposed external to output surface of the first PBS; and a third PBS for synthesizing three image lights, the third PBS has a dicroic characteristics and a polarization characteristics.

Abstract: In a polarization beam splitter that allows effective polarization separation in a wide wavelength range with low dependency on angle of incidence, between two prisms is sandwiched a dielectric multilayer film composed of a first and a second multilayer portion that are designed with respect to a first and a second wavelength &lgr;1, and &lgr;2, respectively. Moreover, the formula &lgr;1<&lgr;2≦155·&lgr;1 is fulfilled, and which is greater of the difference between the refractive indices of the high-refractive-index and low-refractive-index layers in the first multilayer portion and the same difference in the second multilayer portion coincides with which is greater differences of the angles &thgr;1 and &thgr;2 from the prism vertex angle &thgr;.

Abstract: Disclosed herewith is a rear projection optical system for being installed at a rear side of a screen of a rear projection apparatus. The rear projection system comprises: a display panel; a illuminating optical system for illuminating the display panel, the illuminating optical system being decentered from a screen center in both of a horizontal direction and a vertical direction; and a projection optical system, decentered from the screen center in the vertical direction, for projecting a display image on the display panel projected by the illuminating optical system onto a screen through a rear mirror positioned at a position that is the center of the screen. The projection optical system comprises a dioptric system, a deflection mirror, and a curved mirror in this order from the display panel to the rear mirror, and the curved mirror is decentered from the screen center in the vertical direction but centered against the screen center in the horizontal direction.

Abstract: In a polarization beam splitter that allows effective polarization separation in a wide wavelength range with low dependency on angle of incidence, between two prisms is sandwiched a dielectric multilayer film composed of a first and a second multilayer portion that are designed with respect to a first and a second wavelength &lgr;1 and &lgr;2, respectively. Moreover, the formula &lgr;1<&lgr;2<1.55·&lgr;1 is fulfilled, and which is greater of the difference between the refractive indices of the high-refractive-index and low-refractive-index layers in the first multilayer portion and the same difference in the second multilayer portion coincides with which is greater of the differences of the angles &thgr;1 and &thgr;2 from the prism vertex angle &thgr;.

Abstract: A projection optical system has three LCLVs; a first color-separating mirror for separating a substantially polarized light into a first and second color lights and a third color light; a half-wave plate for rotating the polarization direction of either one(s) of the separated light; a second color-separating mirror for synthesizing the first and the third color light, and further, separating the second color light; a first PBS for separating the first and third color lights and illuminating the first and third LCLVs, respectively, and synthesizing image lights from the first and third LCLVs; a second PBS for illuminating the second LCLV and emitting a image light modulated by the second LCLV; a half-wave plate disposed external to output surface of the first PBS; and a third PBS for synthesizing three image lights, the third PBS has a dicroic characteristics and a polarization characteristics.

Abstract: Disclosed herewith is a rear projection optical system for being installed at a rear side of a screen of a rear projection apparatus. The rear projection system comprises: a display panel; a illuminating optical system for illuminating the display panel, the illuminating optical system being decentered from a screen center in both of a horizontal direction and a vertical direction; and a projection optical system, decentered from the screen center in the vertical direction, for projecting a display image on the display panel projected by the illuminating optical system onto a screen through a rear mirror positioned at a position that is the center of the screen. The projection optical system comprises a dioptric system, a deflection mirror, and a curved mirror in this order from the display panel to the rear mirror, and the curved mirror is decentered from the screen center in the vertical direction but centered against the screen center in the horizontal direction.