Abstract: An optical system includes at least one lens and a liquid crystal optical element. The liquid crystal optical element is constructed so that a first liquid crystal lens and a second liquid crystal lens are oppositely arranged so that orientation directions cross at right angles with each other in a plane perpendicular to the optical axis, a voltage applied to the liquid crystal optical element is controlled and a shift of a focal position relative to incident light from a different object point is corrected, and when the liquid crystal optical element does not have a ray deflecting action, a far object point is brought into focus, while when the liquid crystal optical element has the ray deflecting action, a near object point is brought into focus.

Abstract: The invention concerns an optical system adapted to split an optical path from a taking optical system into a finder optical system, which has a camera-shake correction function best suited for the finder optical system, and so on. This optical system comprises a taking optical system and a finder optical system. The taking optical system comprises an optical path splitter means operable to split an optical path into the finder optical system, and the finder optical system includes a relay optical system RLS for re-forming a subject image once. Anti-shake is implemented by shifting an optical subsystem RL that forms a part of the finder optical system in a plane vertical to an optical axis.

Abstract: The invention concerns an optical system adapted to split an optical path from a taking optical system into a finder optical system, which has a camera-shake correction function best suited for the finder optical system, and so on. This optical system comprises a taking optical system and a finder optical system. The taking optical system comprises an optical path splitter means operable to split an optical path into the finder optical system, and the finder optical system includes a relay optical system RLS for re-forming a subject image once. Anti-shake is implemented by shifting an optical subsystem RL that forms a part of the finder optical system in a plane vertical to an optical axis.

Abstract: An optical system includes at least one lens and a liquid crystal optical element. The liquid crystal optical element is constructed so that a first liquid crystal lens and a second liquid crystal lens are oppositely arranged so that orientation directions cross at right angles with each other in a plane perpendicular to the optical axis, a voltage applied to the liquid crystal optical element is controlled and a shift of a focal position relative to incident light from a different object point is corrected, and when the liquid crystal optical element does not have a ray deflecting action, a far object point is brought into focus, while when the liquid crystal optical element has the ray deflecting action, a near object point is brought into focus.

Abstract: An optical system comprises, at least, in order from an object side, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power, wherein at least, the second lens group and the fourth lens group move along an optical axis when magnification is changed from a wide angle end to a telephoto end, and the first lens group contains a light path reflecting element having refracting power.

Abstract: An optical path bending optical system includes, in order from the object side, a first lens unit, a second lens unit with negative power, and at least one lens unit with positive power. When the magnification of the optical system is changed in the range from a wide-angle position to a telephoto position, the lens unit with positive power is moved along the optical axis. The first lens unit is constructed with a prism including a reflecting surface for bending the optical path, an entrance surface, and an exit surface, and has negative power. The entrance surface of the prism is configured as a curved surface with negative power which is rotationally symmetrical with respect to the optical axis.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with negative refracting power, a second lens unit with positive refracting power, and a lens unit with negative refracting power. When the magnification of the zoom lens is changed in the range from a wide-angle position to a telephoto position, at least, the second lens unit is moved along the optical axis, and the first lens unit includes a path-bending element for bending the optical path. The path-bending element includes at least one reflecting surface for bending the optical path, an entrance surface, and an exit surface, and at least one of the entrance surface and the exit surface is configured as a curved surface rotationally symmetrical with respect to the optical axis. Whereby, a slim design of the optical system can be achieved.

Abstract: A vari-focal optical system having a composition comprising at least a first negative lens unit, a second positive lens unit, a third negative lens unit and a fourth positive lens unit, and changes a magnification from a wide position to a tele position by moving at least the second lens unit and the third lens unit. This optical system is configured to have a short total length and reserve sufficient airspaces for the magnification change by locating a front principal point of the second lens unit on the object side of the second lens unit.

Abstract: An optical system comprises, at least, in order from an object side, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power, wherein at least, the second lens group and the fourth lens group move along an optical axis when magnification is changed from a wide angle end to a telephoto end, and the first lens group contains a light path reflecting element having refracting power.

Abstract: A vari-focal optical system having a composition comprising at least a first negative lens unit, a second positive lens unit, a third negative lens unit and a fourth positive lens unit, and changes a magnification from a wide position to a tele position by moving at least the second lens unit and the third lens unit. This optical system is configured to have a short total length and reserve sufficient airspaces for the magnification change by locating a front principal point of the second lens unit on the object side of the second lens unit.

Abstract: An optical path bending optical system includes, in order from the object side, a first lens unit, a second lens unit with negative power, and at least one lens unit with positive power. When the magnification of the optical system is changed in the range from a wide-angle position to a telephoto position, the lens unit with positive power is moved along the optical axis. The first lens unit is constructed with a prism including a reflecting surface for bending the optical path, an entrance surface, and an exit surface, and has negative power. The entrance surface of the prism is configured as a curved surface with negative power which is rotationally symmetrical with respect to the optical axis.

Abstract: The invention relates to a scanning optical system of small size, which is constructed of a reduced number of optical elements. A scanning optical system 10 comprises a prism. In forward ray tracing from a light source 11 to an image plane (the surface to be scanned), a light beam from the light source is collimated by a condensing optical system constructed of a first transmitting surface 1T, a second reflecting surface 1R and a second transmitting surface 2T into a substantially parallel light beam, which is then reflected and deflected at a two-dimensional scanner 12. The reflected and deflected light forms an image through an image-formation optical system constructed of a third transmitting surface 3T, a second reflecting surface 2R, a third reflecting (total reflection) surface 3R and a fourth transmitting surface 4T for two-dimensional scanning of the surface to be scanned.

Abstract: A zoom optical system includes, in order from the object side, a first lens unit with negative refracting power, a second lens unit with positive refracting power, and a lens unit with negative refracting power. When the magnification of the zoom lens is changed in the range from a wide-angle position to a telephoto position, at least, the second lens unit is moved along the optical axis, and the first lens unit includes a path-bending element for bending the optical path. The path-bending element includes at least one reflecting surface for bending the optical path, an entrance surface, and an exit surface, and at least one of the entrance surface and the exit surface is configured as a curved surface rotationally symmetrical with respect to the optical axis. Whereby, a slim design of the optical system can be achieved.

Abstract: The invention relates to a scanning optical system of small size, which is constructed of a reduced number of optical elements. A scanning optical system 10 comprises a prism. In forward ray tracing from a light source 11 to an image plane (the surface to be scanned), a light beam from the light source is collimated by a condensing optical system constructed of a first transmitting surface 1T, a second reflecting surface 1R and a second transmitting surface 2T into a substantially parallel light beam, which is then reflected and deflected at a two-dimensional scanner 12. The reflected and deflected light forms an image through an image-formation optical system constructed of a third transmitting surface 3T, a second reflecting surface 2R, a third reflecting (total reflection) surface 3R and a fourth transmitting surface 4T for two-dimensional scanning of the surface to be scanned.

Abstract: An ocular optical system suitable for a head- or face-mounted image display apparatus which is compact, lightweight and satisfactorily corrected for aberrations, and in which no intermediate image is formed. The image display apparatus includes an image display unit (9) and an optical system (10) for projecting a displayed image into an eyeball (7). The optical system (10) is arranged such that light rays which are emitted from the image display unit (9) and enter the eyeball (7) are reflected at least three times by surfaces (12, 13 and 14) having power in backward ray tracing.

Abstract: A compact, lightweight and wide-field head-mounted image display apparatus which is capable of projecting an image overflowing with a sence of immersion. The apparatus includes an LCD (1), a beam splitter prism (5) having a half-mirror (3) which is disposed at a tilt at an intersection between the optical axis of the LCD (1) and the observer's visual axis to lead an image ray bundle emanating from the LCD (1) to a pupil (4) of an observer's eyeball, and a concave mirror (2) which is provided on a surface of the prism (5) on the side thereof which is remote from the LCD (1). Thus, after entering the prism (5), the image displayed on the LCD (1) is successively reflected by the concave mirror (2) and the half-mirror (3) and then enters the eyeball (4). The effective apertures of the half-mirror (3), the concave mirror (2) and the beam splitter prism (5) are reduced, thereby making the image of the periphery of the image display device unsharp, and thus providing dynamic presence.

Abstract: A head- or face-mounted image display apparatus having compact and wide-field ocular optical systems designed to form readily fusible virtual images. When ocular optical systems having curvature of field are used for observer's right and left eyes, right and left virtual images (13R and 13L) are curved. The right and left ocular optical systems (11R and 11L) having curvature of field are disposed such that the positions of right and left virtual image surfaces are approximately coincident with each other in an area where the right and left virtual image surfaces overlap each other. With this arrangement, a wide field can be ensured, and moreover, the right and left virtual images can be readily fused because the right and left image surface positions are approximately coincident with each other in an area where the right and left image surfaces overlap each other. Accordingly, the user can perform observation with both eyes without fatigue.

Abstract: A compact, lightweight and wide-field head-mounted image display apparatus which is effectively corrected for chromatic aberration. The apparatus includes an image display device (1) for displaying an image, a concave mirror (2) provided to face the image display device (1) to project the displayed image into an eyeball pupil (E) as an enlarged image, and a half-mirror (3) disposed between the image display device (1) and the concave mirror (2). A diffraction optical element (20) having reciprocal dispersion characteristics is disposed somewhere in the optical path to correct chromatic aberration.

Abstract: A projection lens system with a high resolving power and a wide exposure area which is effectively corrected for various aberrations including chromatic aberration and which is compact and has minimal production problems in a case where there is a limitation on vitreous materials usable as a lens material. The projection lens system (10) includes a plurality of lenses, at least one of which is a diffractive optical element (DOE) (11). The DOE (11) has a pitch arrangement in which it has a positive power in a paraxial region thereof, and wherein the positive power continuously changes to a less positive power, and then to a negative power as the distance from the optical axis of the DOE (11) increases toward the periphery thereof. Since the DOE (11) produces large aberrations which are opposite in sign to aberrations produced in the refracting system, it is possible to effectively correct various aberrations in the projection lens system (10) and also axial chromatic aberration.

Abstract: A head-mounted see-through display which enables an outside image and an electronic image to be selectively observed by making a liquid crystal shutter transparent or opaque. To eliminate the problem that during the observation of the electronic image the outside image is undesirably seen through the peripheral region of the electronic image, display light from a two-dimensional display device (11) is first transmitted by a half-mirror (12), and the transmitted light is reflected by a concave mirror (13). Then, the reflected light is reflected by the half-mirror (12) so as to be led to the observer's eye as an enlarged image. To prevent the outside light from entering the eye through the half-mirror (12) during the observation of the electronic image, a negative or positive type TN or STN liquid crystal shutter (10) is disposed in front of the half-mirror (12).