Abstract: An imaging optical system 100 has an imaging side prism 102 for bending incident light at about 90 degrees for reflection, and an image sensor 105 having a light receiving surface opposing to an exit surface 102b of the imaging side prism 102. At least one of an incident surface 101a of an incident side prism 101 and an incident surface 101a of the imaging side prism 102, or at least one of an exit surface 101b of the incident side prism 101 and the exit surface 102b of the imaging side prism 102 has an optical power. An arrangement relation between the exit surface 102b of the imaging side prism 102 and the image sensor 105 is established to satisfy the conditional formula (1): 0.0?d/a<0.8 ??(1) where d represents a distance between the exit surface 102b and the light receiving surface of the image sensor 105, and a represents a height of the light receiving surface of the image sensor 105 on a plane where an optical path of the imaging optical system 100 is folded, e.g.

Abstract: In a zoom optical system for forming an optical image of an object onto a light receiving plane of an image sensor for converting the optical image into an electrical signal, and performing zooming by varying distances between a first lens group and a second lens group, and between the second lens group and a third lens group in an optical axis direction, the zoom optical system includes: the first lens group having a negative optical power; the second lens group having a positive optical power; and the third lens group having a positive optical power, wherein the first lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, the second lens group is composed of two or more lens elements including at least one positive lens element and at least one negative lens element, and all the lens elements in the first lens group are made of a plastic material.

Abstract: A super-wide-angle optical system for forming an optical image of an object on an image pickup surface of an image sensing device that converts the optical image into an electrical signal is provided with, in order from the object side, a first negative lens, a second negative lens and a positive lens. The first negative lens has a meniscus shape convex to the object side. The second negative lens is positioned next to the first negative lens. The positive lens has an aspherical surface. At least one of four lens surfaces of the first and second lenses is an aspherical surface. A prescribed condition is fulfilled.

Abstract: An oblique projection optical system for leading rays of light from a display surface on which an image is displayed to a projection surface in such a way that the ray of light from the center of the display surface is obliquely incident on the projection surface in order to project a magnified image of the image displayed on the display surface onto the projection surface includes a plurality of reflecting surfaces having a power. At least two of the reflecting surfaces have a free-form curved surface, and, of all the reflecting surfaces, the one closest to the projection surface has a negative power and at least one of the other has a positive power. Alternatively, in a rear projection optical system having a projection optical system for projecting an image displayed on a panel display surface onto a screen surface, the projection optical system includes at least four curved-surface reflecting mirrors.

Abstract: A projection image display device has a first display unit for displaying a first image based on a first image signal, an enlarging optical system for enlarging the first image and projecting the first image to the eye of an observer and a second display unit for displaying a second image based on a second image signal and directly projecting the second image to the eye of an observer.

Abstract: An oblique projection optical system for leading rays of light from a display surface on which an image is displayed to a projection surface in such a way that the ray of light from the center of the display surface is obliquely incident on the projection surface in order to project a magnified image of the image displayed on the display surface onto the projection surface includes a plurality of reflecting surfaces having a power. At least two of the reflecting surfaces have a free-form curved surface, and, of all the reflecting surfaces, the one closest to the projection surface has a negative power and at least one of the other has a positive power. Alternatively, in a rear projection optical system having a projection optical system for projecting an image displayed on a panel display surface onto a screen surface, the projection optical system includes at least four curved-surface reflecting mirrors.

Abstract: A tilt projection optical system, that performs enlarged projection from the primary image plane on the reduction side to the second image plane on the enlargement side without forming an intermediate real image while being located at an angled position, has, sequentially from the primary image plane side: a refractive lens group including an aperture; a bending mirror that rotates the optical axis for the optical system after said bending mirror by approximately 90 degrees; and an optical group including at least one reflective surface that has a negative power; wherein the construction is such that the radius of the circle that encompasses all the light rays involved in the image formation on the second image plane and that is parallel to the surfaces of each lens of the refracting lens group enlarges once and then converges in terms of its radius on the enlargement side from the aperture of the refracting lens group, and wherein a predetermined condition is met.

Abstract: An image display apparatus has a reflective display element for displaying a two-dimensional image on a display plane, a light source for emitting illuminating light for illuminating said display plane, a magnifier optical system for magnifying and projecting said two-dimensional image, and an optical member which is composed of a medium having a refractive index greater than or equal to unity and has at least three optical planes of a first plane, a second plane, and a third plane. The magnifier optical system is substantially in concentricity with said display plane; the illuminating light from said light source passes through said first plane and then through said second plane, thereby illuminating said display plane; and the reflected light from said display plane passes through said second plane and is then reflected in said first plane, thereby passing through said third plane and being incident on said magnifier optical system.

Abstract: An oblique projection optical system for leading rays of light from a display surface on which an image is displayed to a projection surface in such a way that the ray of light from the center of the display surface is obliquely incident on the projection surface in order to project a magnified image of the image displayed on the display surface onto the projection surface includes a plurality of reflecting surfaces having a power. At least two of the reflecting surfaces have a free-form curved surface, and, of all the reflecting surfaces, the one closest to the projection surface has a negative power and at least one of the other has a positive power. Alternatively, in a rear projection optical system having a projection optical system for projecting an image displayed on a panel display surface onto a screen surface, the projection optical system includes at least four curved-surface reflecting mirrors.

Abstract: A projection optical system projects an enlarged image of a light valve image onto a screen. The system has, from the conjugate enlargement side: a negative front lens unit, optical path turning means (including a reflecting surface), a positive rear lens unit, and projection light preparing means, which can separate illumination and projection light, or can integrate light of different colors, or can do both. Each of the front and rear lens units includes at least one aspherical surface. The front lens unit has a negative first lens element at its conjugate-enlargement end and a negative second lens element at the conjugate reduction side of the first lens element. The rear lens unit includes a positive third lens element made of an anomalous dispersion material. The center of the light valve is not located on the optical axis of the rear lens unit.

Abstract: A projection optical system that, by using projection light emanating from a light valve illuminated by illumination light, projects an enlarged image of an image displayed on the light valve onto a screen has, from the conjugate enlargement side: a front lens unit having a negative optical power as a whole, including at least one aspherical surface, having a first lens element having a negative optical power disposed at the conjugate-enlargement-side end thereof, and having a second lens element having a negative optical power disposed on the conjugate reduction side of the first lens element; optical path turning means, including a reflecting surface, for turning the light path of the light emanating from the front lens unit; a rear lens unit having a positive optical power as a whole, including at least one aspherical surface, and including a third lens element made of an anomalous dispersion material and having a positive optical power; and projection light preparing means disposed between the rear lens u

Abstract: A display optical system has an illumination optical system for emitting illumination light, a plurality of reflection-type display devices, a projection optical system, and a plane-parallel mirror. The reflection-type display devices individually modulate the illumination light emitted from the illumination optical system and reflect the illumination light thus modulated as projection light. The projection optical system projects the projection light and has at least one optical element included therein arranged so as to be decentered with respect to the other optical elements included therein.

Abstract: An optical projection system used for enlargement projection of an image frame in a two-dimensional display element (P) on a screen (Sb), comprising a first mirror (M1) having negative power on its reflection face and a second mirror (M2) having its reflection face on a light path from the two-dimensional display element to the reflection face of the first mirror, wherein the first mirror (M1) and the second mirror (M2) are disposed on an identical base plate with the first mirror (M1) and the second mirror (M2) being capable of adjusting inclination.

Abstract: An eyepiece optical system for projecting an enlarged virtual image of a two-dimensional image on an observer's pupil has a first reflective/transmissive surface formed as a flat surface, a second reflective/transmissive surface so shaped as to be concave to the pupil side, and a negative-powered optical element having a negative power and arranged between the second reflective/transmissive surface and the two-dimensional image. Here the focal length of the negative-powered optical element f2 and the focal length of the entire eyepiece optical system fs are so determined as to fulfill the following condition: −1.0<fs/f2<−0.1.

Abstract: An oblique projection optical system performing enlargement projection in a slanting direction from a primary image plane to a secondary image plane, or reduction projection in a slanting direction from the secondary image plane to the primary image plane. The oblique projection optical system has at least two lens units each comprising at least one lens element and having surfaces decentered with respect to each other, wherein zooming is performed by moving, of said lens units, a plurality of lens units, and wherein when a ray connecting a center of the primary image plane and a center of the secondary image plane is referred to as an image plane center ray, the predetermined conditions are satisfied without an intermediate real image being formed between the primary image plane and the secondary image plane.

Abstract: A compact, high resolution projection imaged display device using a reflective-type display element which uniformly illuminates the entirety of the display element without reducing illumination efficiency and ensures viewing conditions of excellent and uniform brightness extending to the fringe of the field of view is provided by an illumination optical system for redirecting illumination light from an illumination light source onto a reflective-type display element. The reflective-type display element reflects light into the viewing optical system wherein the illumination optical system is constructed so as to have an approximate conjugate relationship between the pupil of the user and the illumination light from the illumination light source.

Abstract: A focusing method for a decentered optical system including a decentered lens element has translationally moving and inclining at least one lens element for different object distances, in such a way that variation in a position of a primary image point is kept within a range defined by the following condition. Here &Dgr;fb represents a maximum distance traveled by the primary image point during focusing; and &THgr;max represents a maximum angle of peripheral rays traveling from a center of an object to a center of an image plane relative to a base ray: |&Dgr;fb ×sin(&THgr;max)|max≦0.8.

Abstract: A tilt projection optical system that performs enlarged projection from the primary image plane on the reduction side to the second image plane on the enlargement side without forming an intermediate real image while being located at an angled position, said tilt projection optical system has, sequentially from the primary image plane side, a refractive lens group including an aperture; a bending mirror that rotates the optical axis for the optical system after said bending mirror by approximately 90 degrees; and an optical group including at least one reflective surface that has a negative power; wherein the construction is such that the radius of the circle that encompasses all the light rays involved in the image formation on the screen and that is parallel to the surfaces of each lens of the refracting lens group enlarges once and then converges in terms of its radius on the enlargement side from the aperture of the refracting lens group, and wherein the predetermined condition is met.

Abstract: An image display apparatus forms illumination light from a light source into image light by using a reflective display device, and directs the image light through an eyepiece optical system to an eye to present a virtual image of the image carried by the image light. To realize an image display apparatus of this type that is compact, affords a sufficiently long eye relief, and offers wide-field, high-quality images, a combiner for making the optical path of the illumination light from the light source overlap with that of the image light is disposed inside the eyepiece optical system, a positive lens is provided in the rear potion of the eyepiece optical system between the display device and the combiner, a concave reflective surface is provided in the front portion of the eyepiece optical system between the combiner and the observation point, and the eyepiece optical system is designed to be overtelecentric as a whole.

Abstract: An optical system provided with a relay optical system forming an intermediate image of a primary image and an eyepiece optical system projecting an enlarged virtual image of the intermediate image on a pupil. The eyepiece optical system includes, sequentially from the pupil side, a first reflection-transmission surface and a second reflection-transmission surface that is concave on the pupil side, wherein an image surface of the intermediate image has a convex shape relative to the pupil. The optical system satisfies the predetermined condition is satisfied.