Abstract: In a zoom lens (30) comprising, from the object side to the image side, a front lens group (12) and a controllable lens group (24), the controllable lens group comprises two lens elements (25, 26) having different dispersions and being movable with respect to each other so as to perform a focusing action. One of the lens elements corrects for the dispersion of the zoom lens. Preferably, the zoom lens comprises at least one folding mirror.

Abstract: A zoom lens with high optical specification performances and an incorporated electronic imaging system that is much slimmer in its depth direction, albeit having that zoom lens mounted thereon includes a lens group G1 located nearest to the object side, having a reflecting surface M for bending an optical path. The zoom lens satisfies two conditions with respect to a length d as measured along the optical path from the apex of the surface nearest to the object side in lens group G1 to reflecting surface M and a dimension a of the outside shape of a positive lens, found first as viewed along the optical path from the reflecting surface M toward an image side of the zoom lens, in a direction parallel with an optical axis on an object side of the zoom lens with respect to the position where the optical path is bent, respectively.

Abstract: A zoom lens includes a first lens unit fixed when the magnification of the zoom lens is changed and at least two positive lens units arranged on the image side of the first lens unit so that relative spacings between individual lens units are varied when the magnification is changed. The first lens unit has a prism containing a reflecting surface at the most object-side position, the entrance surface of the prism is configured as a concave surface directed toward the object side, and the concave surface is an aspherical surface that divergence is impaired progressively in separating from the optical axis.

Abstract: The present invention provides a variable magnification optical system for forming an optical image of an object on the light-receiving surface of an image sensor with a variable magnification. The variable magnification optical system includes an optical construction comprising, from an object side, a first reflective surface, a first movable unit, a second reflective surface, and a second movable unit. The optical axis is bent at substantially ninety degrees by the first reflective surface and is further bent by the second reflective surface, and, during magnification variation from the wide-angle end to the telephoto end, the first and second reflective surfaces are kept in fixed positions with respect to the image surface, and the first and second movable units move along the optical axis. The variable magnification optical system fulfills a prescribed conditional formula.

Abstract: A finder optical system includes an eyepiece optical system with a positive refracting power. The eyepiece optical system includes an optical unit with a positive refracting power and a lens unit with a positive refracting power, In the eyepiece optical system, a refracting surface that is located most distant from an eyepoint of the eyepiece optical system has a positive refracting power and is configured as an aspherical surface with a negative refracting power on a periphery thereof.

Abstract: A real image mode finder optical system is constructed to be independent of a photographing optical system and includes, in order from the object side, an objective optical system with a positive refracting power, a field frame located in the proximity of the imaging position of the objective optical system, and an eyepiece optical system with a positive refracting power. The real image mode finder optical system has an image erecting means, and the focal length of the objective optical system can be made shorter than that of the eyepiece optical system. In this case, the real image mode finder optical system satisfies the following condition: 0.52<mh/fe<1 where mh is the maximum width of the field frame and fe is the focal length of the eyepiece optical system.

Abstract: The invention relates to a compact, high-performance yet wide-field real image type zoom finder comprising a positive objective optical system Ob and a positive eyepiece optical system Ep and further including an image-inverting means for erecting an real image formed by the objective optical system. The objective optical system Ob comprises a plurality of moving groups G2 and G3, and the eyepiece optical system Ep comprises positive reflecting surfaces, at least one of which is defined by a rotationally asymmetric surface, and satisfies conditions 1.25<dEP/fOC<2.0 and 0.5<lOC/fOC<1.3 where dEP is the distance as measured along an axial chief ray from a final surface to an eye point of the eyepiece optical system, fOC is the focal length of the eyepiece optical system, and lOC is the length as calculated on an air basis and measured along an axial chief ray from an intermediate image-formation plane to the final surface of the eyepiece optical system.

Abstract: The invention provides an optical system that enables focal length, image-formation position, etc. to be controlled in simple construction by bending the optical system to shift a light beam passing through it and so making use of an arbitrary portion of the optical system. In an image-formation optical system comprising at least two optical elements S1 and S2, the at least two optical elements S1 and S2 are mutually decentered to vary the properties such as magnification.

Abstract: An imaging device has a zoom lens system comprising a plurality of lens units and forming an optical image of an object so as to be continuously and optically zoomable by varying a distance between the lens units; and an image sensing element converting the optical image formed by the zoom lens system into an electric signal, wherein the zoom lens system comprises from the object side: a first lens unit having positive optical power as a whole and including a reflecting surface that bends a luminous flux substantially 90 degrees; a second lens unit having negative optical power and disposed with a variable air space from the first lens unit; a third lens unit having positive optical power and disposed with a variable air space from the second lens unit; a fourth lens unit having positive optical power and disposed with a variable air space from the third lens unit; and a fifth lens unit disposed with a variable air space from the fourth lens unit, and wherein zooming is optically performed by varying the air

Abstract: A projection zoom lens system that is suited to a projector with a DMD is provided. The zoom lens system includes a fixed fifth lens group that is positioned on the light modulator side and is used as the field lens that transmits the illuminating light and the projection light and a first lens group for focusing that is fixed during zooming, and is constructed of five groups arranged in negative, positive, positive, negative, positive order from the screen side. The third lens group moves significantly during zooming as a variator, the second and fourth lens groups travel only so small distances as compensators but can correct various aberrations so well. Therefore, the movement of the fourth lens group that is the entrance pupil for the projection light outputted from the light valve is small, so that the active projection light is efficiently taken in and a projection zoom lens system that can project bright, clear images can be provided.

Abstract: A real image mode finder optical system is constructed to be independent of a photographing optical system and includes, in order from the object side, an objective optical system with a positive refracting power, a field frame located in the proximity of the imaging position of the objective optical system, and an eyepiece optical system with a positive refracting power. The real image mode finder optical system has an image erecting means, and the focal length of the objective optical system can be made shorter than that of the eyepiece optical system. In this case, the real image mode finder optical system satisfies the following condition: 0.52<mh/fe<1 where mh is the maximum width of the field frame and fe is the focal length of the eyepiece optical system.

Abstract: A reflecting type of zoom optical system comprises a plurality of optical elements each of which includes a transparent body and two refracting surfaces and a plurality of reflecting surfaces formed on the transparent body and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection by the plurality of reflecting surfaces, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from surface reflecting mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: An optical system comprises, in succession from the object side, a first optical element of negative optical power, a second optical element of positive optical power, and a third optical element of negative optical power, at least one of the first to third optical elements being a refracting optical element having a reflecting curved surface.

Abstract: A real image type view finder comprising an objective optical system which has positive refractive power and forms an intermediate image, an image erecting optical system which erects the intermediate image and an eyepiece optical system which leads the intermediate image to an observer's eye, in which the objective optical system comprises a first positive lens unit, a second negative lens unit, a third negative lens unit and a fourth positive lens unit, moves the second lens unit and the third lens unit for a magnification change, has a vari-focal ratio on the order of 4, and has favorable optical performance over an entire zooming region.

Abstract: An optical turning film has a first surface including an array of prisms. The array has a plurality of first prisms, with each of the first prisms having a first prism configuration, and a plurality of second prisms, with each of the second prisms having a second prism configuration different from the first prism configuration. The optical film also has a second surface opposing the first surface, and light rays incident to the first surface are directed by the plurality of first prism and the plurality of second prisms along a direction substantially parallel to a viewing axis.

Abstract: A projection system that is capable of providing a high-performance projection system and producing a high contrast projection image by using an optical modulation element, which can be positioned a predetermined distance away from an illumination optical system and a projection optical system. The optical modulation element is capable of modulating light received from the illumination optical system and projecting the modulated light to a projection optical system in the direction of a projection surface.

Abstract: The invention relates to optical elements comprised of an optical isotropic completely aromatic polyester with a glass transition temperature Tg≧180° C.

Abstract: A shift in focal point due to longitudinal chromatic aberration of a photographing lens is properly corrected in accordance with various photographing conditions, by means of controlling the thickness of a variable-thickness optical filter interposed between an image pickup lens system and a solid-state image pickup element, on the basis of a correlation table defining the correlation between photographing conditions and the thickness of the variable-thickness optical filter that can correct a shift in focal point. A variable-thickness optical filter is interposed between a photographing lens system and a CCD having sensitivity ranging from the visible-light range to the infrared range. The thickness of the optical filter is changed, by means of controlling an actuator on the basis of a correlation table defining the correlation between the photographing conditions and the thickness of the variable-thickness optical filter which can correct the shift in optical focal point.

Abstract: Methods and apparatus for reconfiguring a generally elliptically shaped beam produced by a laser diode bar into a single modified beam of substantially symmetrical shape. The methods and apparatus include the provision and utilization of a prism assembly which includes an entrance aperture, an exit aperture, and four total internal reflection surfaces. An incident beam is totally reflected at the total internal reflection surfaces step by step and is chopped into a specific number of parts which have the same width as that of the exit aperture from which they emerge stacked one on top of another. Three embodiments, according to the types of prism assemblies and entrance and exit apertures, are presented.

Abstract: A zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. Each lens unit has a plurality of lens units. One embodiment has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power wherein the second lens unit has at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments have more or fewer lens units and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: A zoom optical system is disclosed. The zoom optical system provides a series of lens units designed to allow for zooming with minimal change in aberration resulting from the movement of the lens units. To achieve this goal each lens unit is has a plurality of lens units. By way of example, one embodiment of the present invention has, in order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power wherein the second lens unit comprises at least one gradient index lens element and the first lens unit is kept stationary during a change of magnification. Additional embodiments are described in which more or fewer lens units are used and the refractive power of each lens unit is varied. In some embodiments, a lens unit other than the first lens unit is kept stationary.

Abstract: A prism-type objective lens is provided for use in the pickup head of an optical disc drive capable of driving two types of optical discs such as a CD and a DVD. The prism-type objective lens allows the pickup head to be made more compact in size with reduced structural complexity, and also allows the pickup head to read data from two different types of optical discs. The prism-type objective lens includes a prism having a cross section substantially in the shape of a right triangle, a front aspherical plano-convex lens, and a rear aspherical plano-convex lens, where the planar surface of each lens is attached to one or the other of the leg sides of the prism. The hypotenuse side of the prism can be formed with two aperture areas where different reflective layers are coated. Alternatively, the hypotenuse side of the prism can be formed with a reflective HOE layer that allows the laser beam incident on it and reflected from it to be diffracted into two beams which are focused at different points.

Abstract: A high-performance real-image finder with a zoom objective optical system wherein a power is given to a reflecting surface of an image-inverting optical system to reduce the size in the direction of the thickness, and at the same time, a rotationally asymmetric surface is used in the image-inverting optical system to correct rotationally asymmetric decentration aberrations. The zoom objective optical system Ob has a first lens unit G1 of negative power, a second lens unit G2 of positive power, and a third lens unit G3 of positive or negative power. The real-image finder further includes an image-inverting optical system PP for erecting an intermediate image formed by the objective optical system Ob, and an ocular optical system Oc having a positive refracting power. At least one of reflecting surfaces S.sub.8 and S.sub.

Abstract: A zoom lens comprises a plurality of optical elements each of which includes a transparent body having two refracting surfaces and a plurality of reflecting surfaces and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from front surface mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: A zoom lens system that is free from parallax, is compact, and offers excellent optical performance has, from the object side, a positive first lens unit, a negative second lens unit, a positive third lens unit, and a negative fourth lens unit. The zoom lens system has a half-prism between the second lens unit and the third lens unit so that a light beam having passed through the second lens unit is split by reflection.

Abstract: A compact endoscope optical system capable of providing a clear image of minimal distortion even at a wide field angle. The endoscope optical system includes an objective optical system for forming an object image. The objective optical system has a prism member (3) having reflecting surfaces (5, 6) for bending an optical path. The endoscope optical system further includes an image transfer system for leading the object image formed by the objective optical system to an observation apparatus along the direction of a major axis. The objective optical system has a configuration producing decentration aberration by bending the optical path. The prism member (3) has at least one curved surface (4 to 7) having an optical action in the optical path. The curved surface is such a non-rotationally symmetric surface having no axis of rotational symmetry in nor out of the surface as to correct the decentration aberration.

Abstract: An image stabilizer has, in succession from the object side, an objective lens group having at least positive refractive power, variable angle prism having its vertical angle variable, and optical prism, and which satisfies the following condition:-20<.nu..sub.VAP -.nu..sub.RP <40,when .nu..sub.VAP is the Abbe's number of the variable angle prism, and .nu..sub.RP is the mean value of the Abbe's number of the optical prism.

Abstract: A finder optical system of the present invention includes from the object side an objective lens system of a positive refractive power and an eyepiece system of a positive refractive power. The objective lens system includes from the object side a first lens unit of a negative refractive power, a second lens unit of a positive refractive power and a third lens unit of a positive refractive power. Zooming is performed by moving the first and second lens units. Each of the first and second lens units includes a single lens having at least one aspherical surface. The third lens unit includes a lens prism at least an incident surface of which is an aspherical surface.

Abstract: A plural beam optical head is constituted by an optical system for imaging a plurality of light beams onto an optical information recording medium, a double-refractive crystal prism and a sensor. The plurality of light beams obtained from the optical information recording medium are separated into components the polarized direction of which are orthogonal one another by the double-refractive crystal prism. The direction of arrangement of the plurality of light beams incident on the double-refractive crystal prism is substantially perpendicular to the direction of separation of the light beams obtained from the double-refractive crystal prism. The light beams from the double-refractive crystal prism are received by the sensor.

Abstract: A stereoscopic glasses of a construction, in which left and right lenses are formed into a single integral body, which is fitted into a lens frame and maintained in it.

Abstract: An image stabilization optical system for use in the variable magnification optical system having a first lens group followed rearwardly by a zoom section comprising a plurality of lens groups is disclosed, wherein as at least one lens group in the zoom section is made to be a compensating lens group, the optical action of each lens group is properly specified so that if the tilting of the optical system is the same, the amount of compensation movement of the compensating lens group becomes always the same regardless of the image magnification varying position.

Abstract: The invention relates to a motor vehicle headlight glass suitable for being mounted in a position where it slopes relative to a vertical plane, and being of the type that comprises a plurality of stripes for the purpose of spreading the light emitted by the headlight substantially in a lateral direction. Each stripe in at least one given group of stripes has a stripe surface which is ruled and without slope discontinuity, having tangency planes which define a set of unit prisms whose prism angles and whose slopes relative to the vertical vary together in such a manner that an incident ray on any one of the prisms is deflected laterally by the prism by an amount that varies depending on the prism, but without being subjected to vertical deflection. The invention also provides a method of making a mold die for mass producing the glass, and a method of manufacturing the glass by molding.

Abstract: A Kepler-type erect image viewfinder includes a first prism having an emergent surface being formed of a spherical or an aspherical surface and having a positive power. A second prism has an incident surface being formed of a spherical or aspherical surface and also having a positive power. The emergent surface of the first prism is spaced apart from the incident surface of the second prism, with an image-forming plane being positioned closer to the incident surface of the second prism than the emergent surface of the first prism. This arrangement enhances image magnification and compensates for field curvature, while simultaneously allowing for the viewfinder to have a reduced overall length.