Abstract: A high-performance lens system including lens elements of small diameters for projecting on to a screen or the like in an enlarged fashion images from light valves such as mainly DMDs (Digital Micromirror Devices) for forming images by changing reflecting directions of light. A lens system is provided which includes, sequentially in that order from a magnifying side, a first lens group which makes up a substantially a focal optical system as a whole and a second lens group having a positive refractive power as a whole, and depending upon applications, a third lens group made up of a single positive lens element is provided in the vicinity of a light valve such as a DMD on a contracting side of the second lens group.

Abstract: An optical system includes a first optical element and a second optical element on at least one of an enlargement side and a reduction side relative to a point P at which a light axis and a paraxial chief ray intersect. Each of the first optical element and second optical element is composed of a solid material having a refractive light incident surface and a refractive light emergent surface. The optical system satisfies the following conditional expressions: ??gF1>0.0272, ??gF2<?0.0278, and f1×f2<0 where ??gF1 and ??gF2 denote anomalous partial dispersion values of the first and second optical elements for the g-line and F-line, respectively, and f1 and f2 denote focal lengths of the first and second optical elements, respectively, when the light incident surfaces and the light emergent surfaces of the first and second optical elements are in contact with air.

Abstract: A lens system (46) that can be used in a digital camera includes, in sequence, a first lens element (20), a second lens element (30) and a third lens element (40). The first lens element is biconvex and includes a first spherical surface (22) and a second spherical surface (24). The second lens is concavo-convex and includes a first aspheric surface (32) and a second aspheric surface (34). The first aspheric surface is a diffractive surface. The third lens includes a wave-shaped third aspheric surface (42) and a wave-shaped fourth aspheric surface (44). The lens has a compact volume and provides stable imaging performance and good image quality.

Abstract: An image-forming lens set includes an aperture stop, a first lens with positive power, a second lens with negative power and a third lens, which are arranged from an object side order. The first lens has two opposite surfaces including a convex surface facing the object side, and at least one of the two opposite surfaces is a non-spherical surface. The second lens has two opposite surfaces including a concave surface facing the object side, and at least one of the two opposite surfaces of the second lens is a non-spherical surface. The third lens has negative refractive power becoming greater from a center to a periphery of positive refractive power. The third lens has two non-spherical opposite surfaces including a convex surface facing the object side. At least one of the first, second and third lenses is coated with a layer of optical film for filtering light.

Abstract: A wide-angle lens system includes a negative first meniscus lens element, a positive second lens element, a positive third biconvex lens element, and a negative fourth meniscus lens element, in this order from the object; wherein said wide-angle lens system satisfies the following condition: 0.25<H/(p3+p4)<0.60 wherein H designates the distance between the second principal point of the positive third biconvex lens element and the first principal point of the negative fourth meniscus lens element, when the focal length of the entire wide-angle lens system is normalized to 1.0; p3 designates the refractive power of the positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0; f3 designates the focal length of the positive third biconvex lens element when the focal length of the entire wide-angle lens system is normalized to 1.0, i.e.

Abstract: An image-forming lens set includes a first lens, a second lens, an aperture and a third lens arranged orderly from an objective side toward an image side in sequence. The first lens is made of plastic material and has a positive diopter and two opposite surfaces including a convex surface facing the image side. The second lens is made of plastic material and has a negative diopter and two opposite surfaces including a concave surface facing the image side. The third plastic lens is made of plastic material and has a positive diopter and two opposite surfaces including a convex surface facing the image side.

Abstract: A compact zoom lens suitable for an imaging optical system using a solid-state image sensing device is provided. The zoom lens includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first through third lens groups are sequentially arranged from an object side toward an image side. The first, second, and third lens groups move when magnification changes from the wide-angle position to the telephoto position, and a refractive index G1n of at least one lens element included in the first lens group satisfies 1.90<G1n<2.00.

Abstract: A four-piece lens assembly, from the object side, comprises: an aperture, a first lens, a second lens, a third lens, a fourth lens, a flat parallel glass and an image plane. The first lens is a double convex positive lens. The second lens is a double concave negative lens or a plano-concave lens whose object side surface contacts the image side surface of the first lens. The first and second lenses contact each other in such a manner that the concave surface of the connecting surface faces the object side, and the concave surface (or plano surface) of the second lens faces the image plane. The first and second lenses are made of high refractive index material. The lens assembly not only can ensure a necessary back focus but also can suppress the total length of a portable image taking device.

Abstract: It is to provide an imaging lens that can maintain optical performance and actualize size and weight reduction. The imaging lens comprises, in order from an object side to an image surface side, a first lens that is a meniscus lens having a positive power whose convex surface faces the object side, a diaphragm, a second lens that is a meniscus lens having a positive power whose convex surface faces the image surface side, and a third lens that is a biconcave lens having a negative power, wherein a condition expressed by 0.11<d4/fl?0.25 (where, d4: distance between the second lens and the third lens on the optical axis, and fl: focal distance of the entire lens system) is to be satisfied.

Abstract: It is to provide an imaging lens that can maintain optical performance and actualize size and weight reduction. The imaging lens comprises, in order from an object side to an image surface side, a first lens that is a meniscus lens having a positive power whose convex surface faces the object side, a diaphragm, a second lens that is a meniscus lens having a positive power whose convex surface faces the image surface side, and a third lens that is a biconcave lens having a negative power, wherein conditions expressed by 0.023?d4/fl?0.11 and 0.068<f1/f2?0.8 (where, d4: distance between the second lens and the third lens on the optical axis, fl: focal distance of the entire lens system, f1: focal distance of the first lens, and f2: focal distance of the second lens) are to be satisfied.

Abstract: A wide angle lens includes, in order from an object side, a first positive convex lens element, a second concavo-convex negative lens element, and a third lens element. The first lens element is made of an optical glass and defines a first convex aspheric surface on the object side and a second plane aspheric surface. The second lens element is made of an optical plastic and defines a third concave aspheric surface on the object side and a fourth convex aspheric surface. The third lens element is made of an optical plastic and defines a fifth high-aperture size convex aspheric surface on the object side and a sixth wave-shaped aspheric surface. Each of the lens elements is symmetrically disposed about an optical axis of the lens. The lens is compact and capable of covering total field angle of up to about 70 degrees.

Abstract: An optical system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first lens element with negative refractive power, a second lens element with positive refractive power, and a third lens element with positive refractive power, wherein an aperture stop is located behind the first lens element, each of at least two lens elements is provided with at least one aspheric surface. By such arrangements, the optical system can obtain a good image quality, maintain enough back focal length and increase the field of view of the optical system.

Abstract: In a liquid immersion type projection optical system for forming an image of a first plane on a second plane, an optical path between the optical system and the second plane is filled with a liquid having the refractive index larger than 1.5, and the optical system has a boundary optical element whose surface on the first plane side is in contact with a gas and whose surface on the second plane side is in contact with the liquid. The optical system satisfies the condition of 3.2<Nb·Eb/|Rb|<4.0, where Rb is a radius of curvature of the surface on the first plane side of the boundary optical element, Eb an effective diameter of the surface on the first plane side of the boundary optical element, and Nb a refractive index for used light, of an optical material forming the boundary optical element.

Abstract: A single focus imaging lens comprises: a front lens group including one or two lenses and having a positive refractive power as a whole; a rear lens group including two or three lenses and having a negative refractive power as a whole; and a focusing lens, disposed between the front lens group and the rear lens group, that has a positive refractive power and moves on an optical axis for adjusting focus, wherein the following conditional expression is satisfied: 1.0<FL/f<5.0 ??(X) where f: focal length of the single focus imaging lens; FL: focal length of the focusing lens.

Abstract: A portable projection device comprises a housing, a handle, and an optical engine. The optical engine comprises an illumination source, an imaging system, and a wide angle projection lens that includes a first lens group of negative refractive power, the first lens group having at least one aspheric surface, a second lens group, and a third lens group of positive refractive power. For the wide angle projection lens, the following Conditions (1) to (4) are satisfied: |F1/F|?4.5 (Condition (1)); 2.5?|F2/F|?6.0 (Condition (2)); 3.8?|F3/F|?5.0 (Condition (3)); and 0.8?BFL/F?1.4 (Condition (4)). The portable projection device can be implemented as a personal gaming system and can also be configured as a portable, fully integrated video gaming system that allows gamers to plug in and play at nearly any location, with only a wall or other viewing surface being used to view the projected image.

Abstract: In an imaging lens of the present invention, various types of aberration are corrected favorably, the optical length is short, and a sufficient back focus is secured. The imaging lens comprises an aperture diaphragm S1, a first lens L1, a second lens L2, and a third lens L3, and is constituted such that the aperture diaphragm, first lens, second lens, and third lens are arranged in succession from the object side toward the image side. The first lens has a positive refractive power and convex surfaces facing the object side and the image side. The second lens has a negative refractive power, a meniscus shape, and a convex surface facing the image side. The third lens L3 has a positive refractive power and convex surfaces facing the object side and the image side. Both surfaces of the first lens, both surfaces of the second lens, and both surfaces of the third lens L3 are aspherical.

Abstract: A three-piece lens assembly comprises: a first lens group, a second lens group, a third lens group and an aperture. The first lens group is a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture. The second lens group is a positive meniscus lens with a concave surface facing the aperture and the object side. The third lens group is a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, and the concave surface of the third lens facing the object side is greater than the another surface of the third lens facing the image side in radius of curvature. Both sides of the first, second and third lens groups are aspheric and are all made of plastic material.

Abstract: An object is to provide a high-resolution zoom lens system which has fewer lens elements and therefore, can be retracted into a compact form when not in use; and the zoom lens system, in order from the object side, comprises a first lens unit G1 having negative power, a second lens unit G2 having positive power and a third lens unit G3 having positive power, wherein magnification is varied with change in intervals between each lens unit by independently moving each lens unit along an optical axis, in which the first lens unit G1 comprises one negative lens element L1 and one positive lens element L2, the second lens unit G2 comprises only a cemented lens element having set of three lens elements L3, L4 and L5 which are cemented with each other, and the third lens unit G3 comprises one positive lens element L6.

Abstract: A projection lens includes, in order from a magnification side, a first lens group, a second lens group and a third lens group. The first lens group includes, in order from the magnification side, a negative lens whose lens made of a non-resin, a plastic lens at least one surface of which is aspheric and a positive lens. The second lens group includes a plastic lens at least one surface of which is aspheric, a positive lens and a negative lens. The third lens group includes a positive lens. The following conditional expressions are satisfied; 1.0<Bf/f?1.8 2.0<f1/f 2.0<f2/f where Bf denotes a air-conversion back focus of the entire system, f denotes a focal length of the entire system, f1 denotes a focal length of the first lens group and f2 denotes a focal length of the second lens group.

Abstract: A dual field of view lens system comprising a first lens group aligned along an optical axis and a third lens group aligned along the optical axis and positioned a predetermined distance from the first lens group. A second lens group, having an optical stop attached thereto, is aligned along the optical axis and disposed between the first and third lens group such that the second lens group and the optical stop are moveable along the optical axis between a first position and a second position. Positioning the second lens group and the optical stop in the first position provides a wide field of view and moving the second lens group and the optical stop to a second position provides a narrow field of view.

Abstract: An imaging optical system includes an aperture stop, a positive first lens group, and a positive or negative second lens group. The first lens group includes a positive first lens element and a negative second lens element. The first lens element is provided with an aspherical surface on the object-side surface thereof. The aspherical surface is formed so that the higher a height from the optical axis in a radial direction becomes the more an aspherical surface at the height is displaced toward the object, compared with a paraxial spherical surface. The second lens group includes a meniscus third lens element. The meniscus third lens element is provided with an aspherical surface on each lens surface thereof, and has the convex surface facing toward the object in the vicinity of the optical axis.

Abstract: A dual field of view lens system comprising a first lens group aligned along an optical axis and a third lens group aligned along the optical axis and positioned a predetermined distance from the first lens group. A second lens group, having an optical stop attached thereto, is aligned along the optical axis and disposed between the first and third lens groups such that the second lens group and the optical stop are moveable along the optical axis between a first position and a second position. Positioning the second lens group and the optical stop in the first position provides a wide field of view and moving the second lens group and the optical stop to a second position provides a narrow field of view.

Abstract: A wide-angle lens system includes: from the object side, (1) a first lens element formed of glass having both surfaces thereof so formed as to be spherical, having a meniscus shape convex to the object side, and having a negative optical power; (2) a second lens element formed of plastic having a meniscus shape convex to the image side and having a positive optical power; (3) an aperture stop; and (4) a third lens element formed of plastic having a meniscus shape convex to the image side and having a positive optical power, and the wide-angle lens system includes three lens elements in total. This permits providing a low-cost, compact super-wide-angle lens system having a favorable optical performance.

Abstract: The invention relates to an image-formation optical system that meets both demands for high performance and compactness, and an imaging system that incorporates the same. The imaging system is built up of an image-formation optical system comprises, in order from its object side, an aperture stop S, a first positive single lens L1 wherein the absolute value of the axial radius curvature of its image side-surface is smaller than that of its object side-surface, a second negative single lens L2 wherein the absolute value of the axial radius curvature of its image side-surface is smaller than that of its object side-surface and a third positive single lens L3, three single lenses in all, and an image pickup device located on the image plane I of the image-formation optical system.

Abstract: An imaging lens comprises, in order from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power whose concave surface faces to the object; and a third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens; wherein the first, second and third lenses have at least one aspheric surface, and wherein the imaging lens satisfies conditional expressions given below: 0.7<f1/f<1.3??(1) 0.2<D2/f<0.6??(2) 0.3<|f2/f|<0.8??(3) 0.5<f3/f<0.8??(4) where f: a focal length of an overall system, f1: a focal length of the first lens, f2: a focal length of the second lens, f3: a focal length of the third lens, and D2: a spacing, on the optical axis, between the first lens and the second lens.

Abstract: Provided is a zoom lens which is telecentric on a reduction side, including a plurality of lens units, in which the zoom lens satisfies the following conditions: ?dp>75 fw/fp<0.6 where ha indicates a height of a paraxial marginal ray passing through the zoom lens, and hb indicates a height of a paraxial chief ray passing through the zoom lens, where, among a plurality of positive lenses in the zoom lens, a positive lens whose hb/ha is the smallest is defined as a smallest positive lens in at least a part of a zoom range from a wide-angle end to a telephoto end, and where ?dp indicates an Abbe constant of a material of the smallest positive lens, fp indicates a focal length of a lens unit including the smallest positive lens, and fw indicates a focal length of an entire system at the wide-angle end.

Abstract: An object is to provide an imaging lens system which can achieve reduction of the size and weight while maintaining the high optical performance. The imaging lens system of the present invention comprises, in order form an object side to an imaging surface side: a first lens having a positive power with its convex surface facing the object side; a second lens in a meniscus shape having a positive power with its concave surface facing the object side; and a third lens functioning as a correction lens, wherein the imaging lens system satisfies following expressions: 0.25<r1/f<0.50, and ?0.27<r3/f<?0.19 (where, r1: a radius of center curvature of the surface (first face) of the first lens on the object side, r3: a radius of center curvature of the surface (first face) of the second lens on the object side, f: a focal distance of an entire lens system).

Abstract: At least one exemplary embodiment is directed to a zoom lens which includes, in order from an object side to an image side, a first lens unit with a negative refractive power, a second lens unit with a positive refractive power, and a third lens unit with a positive refractive power. A first gap between the first and second lens units when the zoom lens is at a wide-angle end is smaller than the first gap when the zoom lens is at a telephoto end, where a second gap between the second and third lens units when the zoom lens is at the wide-angle end is larger than the second gap when the zoom lens is at the telephoto end. The second lens unit includes at least one positive cemented lens.

Abstract: An imaging lens comprises, in order from an object side: an aperture stop; a first lens having a positive refractive power in a meniscus form having a convex surface facing toward the object; a second lens having a positive or negative refractive power in a meniscus form having a concave surface facing toward the object; and a third lens having a positive or negative refractive power in an aspheric form at both surfaces, wherein conditional expressions given below are satisfied: vd1>50 ??(1) vd3>50 ??(2) 0.7<f1/f<1.0 ??(3) ?0.9<f2/{f3·(45?vd2)}<0.4 ??(4) where vd1: Abbe number of the first lens, vd2: Abbe number of the second lens, vd3: Abbe number of the third lens, f: Focal length of an overall system, f1: focal length of the first lens, f2: focal length of the second lens, and f3: focal length of the third lens.

Abstract: An imaging lens comprises, in order from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power whose concave surface faces to the object; and a third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens; wherein the first, second and third lenses have at least one aspheric surface, and wherein the imaging lens satisfies conditional expressions given below: 0.7<f1/f<1.3 ??(1) 0.3<D2/f<0.5 ??(2) 1.0<|f2/f|<3.0 ??(3) 1.2<f3/f<4.0 ??(4) where f: a focal length of an overall system, f1: a focal length of the first lens, f2: a focal length of the second lens, f3: a focal length of the third lens, and D2: a spacing, on the optical axis, between the first lens and the second lens.

Abstract: Providing a compact zoom lens system having a high zoom ratio. The zoom lens system includes, in order from an object, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a third lens group G3 having positive refractive power. When a state of lens group positions varies from a wide-angle end state W to a telephoto end state T, at least the first lens group G1 and the third lens group G3 are moved along the optical axis to the object. Given conditional expressions are satisfied.

Abstract: A wideband, e.g., 550 nm to 940 nm, apochromatic lens system for use with an external aperture stop, includes first, second, and third optical groups having, in order, positive, negative, and positive powers. The first group includes four optical elements having, in order, negative, positive, negative, and positive powers. The second group includes one element of negative power; and the third group includes two elements each having positive power. In another embodiment for use with an internal stop, the system includes first, second, and third optical groups having, in order, positive, positive, and negative powers. The first group includes four optical elements having, in order, positive, negative, positive, and negative powers. The second group includes one element of positive power, and the third group includes one element of negative power. In either embodiment, all of the optical elements are formed from not more than three different types of glass material.

Abstract: An endoscope objective lens is provided and has a front-group divergent lens system, an aperture stop, and a rear-group convergent lens system in this order from the object side. The back focal length Bf of the whole system is longer than 2.5 times the combined focal length f of the whole system. The rear-group convergent lens system includes a cemented lens. The endoscope objective lens satisfies the specific formula.

Abstract: An image pick-up lens system includes an aperture stop (10), a biconvex first lens (20), a second lens (30) having a concave surface on an object side, and a third lens (40) having a concave surface on an image side. The aperture stop (10), the first lens (20), the second lens (30) and the third lens (40) are aligned in that order from the object side to the image side. All lenses in the system are made from a plastic or resin material, and one of them has a diffraction grating formed on a surface. The system satisfies conditions (1)-(5) as disclosed, in order to provide compactness, cost-effectiveness and improved optical performance.

Abstract: A four-piece lens assembly, from the object side, comprises: an aperture, a first lens, a second lens, a third lens, a fourth lens, a flat parallel glass and an image plane. The first lens is a double convex positive lens. The second lens is a double concave negative lens or a plano-concave lens whose object side surface contacts the image side surface of the first lens. The first and second lenses contact each other in such a manner that the concave surface of the connecting surface faces the object side, and the concave surface (or plano surface) of the second lens faces the image plane. The first and second lenses are made of high refractive index material. The lens assembly not only can ensure a necessary back focus but also can suppress the total length of a portable image taking device.

Abstract: A compact lens system includes, in succession from an object side to an image side, an aspheric first lens element (1) having a positive power, an aperture stop (4), an aspheric second lens element (2) having a negative power, and a third lens element (3) having a positive power. Both the first and second lens elements are meniscus lenses made of plastic, and the third lens element is a biconvex lens or a plano-convex lens made of glass. The first lens element has a convex surface (10) facing the object side and an opposite concave surface (11) facing the aperture stop. The second lens element has a concave surface (21) facing the aperture stop and an opposite convex surface (20) curved toward the image side. The surface (30) of the third lens element facing toward the image side has a radius of curvature larger than that of the other surface (31) facing the second lens element.

Abstract: The invention relates to an electronic imaging system wherein an image pickup device is horizontally located while ensuring the space for a reflective member thereby achieving height, length and cost reductions. The imaging system comprises a taking lens and an image pickup device. The taking lens comprises a front lens group G1 consisting of a negative lens component and a positive lens component and having positive refracting power and a rear lens group G2 consisting of a negative lens element and a positive lens element and having positive refracting power, with an aperture stop S interposed between the front lens group G1 and the rear lens group G2. The taking lens satisfies conditions (1) and (2). 2.8<fB/IH<4.5 ??(1) 2<SF<3 ??(2) Here fB is back focus of the taking lens, IH is a length that is half the diagonal length of the effective plane of the electronic image pickup device, and SF is a shape factor for the negative lens component in the front lens group.

Abstract: A zoom lens formed in a small size adaptable to a thin and portable device, having three lens groups, including, from the object plane to the image forming plane: a first lens group with a negative power, a second lens group with a positive power and a third lens group with a positive power. By controlling the ratio of the focal length of the second lens group and the focal length of the tele-photo end, image distortion may be controlled, and the total length of the lens may be reduced to shrink the size of the lens. Hence production costs may be reduced, which is important to mass production.

Abstract: To provide an endoscope objective lens which has a lens constitution of a relatively small number of three pieces, a short total length of lens, and various kinds of good optical performances starting with curvature of field. It is constituted of a first lens L1 directing its concave surface to the image side, a second lens L2 made of a positive meniscus lens directing its convex surface to the image side, and a third lens L3 made of a planoconvex lens directing its convex surface to the object side arranged sequentially from the object side, and a stop placed between said first lens L1 and said second lens L2. It also satisfies the following Conditional Expressions: 2.00<|f1/f|<3.00,??(1) 0.50<|f2/f3|<0.70,??(2) 2.00<|f1/d1-2|<5.00 ,??(3) 0.40<|R2R/R2F|<0.60 .

Abstract: A taking lens system includes, in order from an object side thereof, a first lens group (negative refracting), a second lens group (positive refracting), an aperture stop and a third lens group (positive refracting). Focusing from an infinite distance to a finite distance is performed by setting the second lens group and the third lens group such that the position of the second lens group upon focusing on a finite distance is located on an image side of the taking lens system with respect to the position of the second lens group upon focusing on an infinite distance and the position of the third lens group upon focusing on a finite distance is located on an object side of the taking lens system with respect to the position of the third lens group upon focusing on an infinite distance, while the first lens group remains fixed.

Abstract: A lens system including a first substantially hemispherical lens, a second spherical lens and a third substantially hemispherical lens. The lenses are held together by a bonding material such as epoxy, which may also include a light absorbing dye. The invention also relates to a low-cost method of manufacturing the lens system out of glass, using low cost glass ball lenses to create the hemispherical lenses.

Abstract: A zoom lens system includes a first lens group which has a negative refractive power, a second lens group which has a positive refractive power, and a third lens group which has a positive refractive power in this order from the object side and changes the distances among these lens groups to vary the power from the wide-angle end to the telephoto end. The second lens group has a three-element cemented lens including a positive lens c1, a negative lens c2, and a positive lens c3.

Abstract: Providing a compact zoom lens system having high optical performance suitable for an electronic imaging device with a large number of pixels. The zoom lens system includes, in order from an object, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. When zooming from a wide-angle end state to a telephoto end state, the first lens group and the second lens group are moved such that a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases. The second lens group is composed of at least two positive lens elements and one negative lens element. At least one positive lens element and the negative lens element in the second lens group satisfy given conditional expressions.

Abstract: A lens system (46) for a digital camera consecutively includes a first lens element (20), a second lens element (30), and a third lens element (40). The first lens element is biconvex and has a first aspheric surface (22) and an opposite second aspheric surface (24). The second lens element is concavo-convex and includes a third aspheric surface (32) and an opposite fourth aspheric surface (34). The third lens element convexo-concave and has a fifth aspheric surface (42) and an opposite sixth aspheric surface (44). The first lens element is made of glass, and the second lens element and the third lens are made of optical plastic.

Abstract: A single focus lens comprises: a first lens of positive power having a convex-shaped surface on an object side; a second lens of a negative meniscus lens having, on the object side, a concave-shaped surface on its paraxial axis; and a third lens of an aspheric lens having, on the object side, a convex-shaped surface on its paraxial axis, in this order from the object side, wherein the single focus lens satisfies the predetermined conditions.

Abstract: A Fourier transform lens system includes: a first lens group having negative power and a second lens group having positive power disposed at one side of the first lens group with the first lens group and the second lens group being arranged on a common optical axis. The first lens group includes two negative meniscus lenses each having negative power, and each of the negative meniscus lenses has a concave lens surface facing toward a concave lens surface of the other negative meniscus lens. The second lens group includes a positive lens having a convex lens surface facing toward the first lens group. The Fourier transform lens system satisfies the following conditions: (1) 0.1<R1R/f<0.4; (2) ?0.4<R2F/f<?0.1; and (3) 0.1<d12/f<0.3. A holographic storage system using a Fourier transform lens system is also provided.

Abstract: An aspherical type imaging lens array comprises, from object side to image side, at least an aperture, a first positive meniscus lens with a convex surface facing the object side, a second meniscus lens with a convex surface facing the image side, and a third lens meniscus lens with a convex surface facing the object side. The respective lenses are made of plastic and has two aspherical surfaces, a focal length of the aspherical type imaging lens array is f, a focal length of the second lens is f2, and a focal length of the third lens is f3, they satisfy the equation: ?0.20<f/f2<0.15, and ?0.25<f/f3<0.20.

Abstract: A hybrid lens system includes, in order from an object side to an image side: a first positive lens, a second negative lens, and a third positive lens. The first lens is made of glass material. The second and second lenses are both made of plastic material and respectively have two aspheric surfaces. The hybrid lens system is capable of resisting scraping and providing high imaging quality.

Abstract: A single focus wide-angle lens includes, in order from the object side: a first lens component of positive refractive power, having a meniscus shape, and having a convex object-side surface; a stop; a second lens component of positive refractive power, having a meniscus shape, having at least one aspheric surface, having a concave object-side surface, and being made of plastic; and a third lens component of negative refractive power, having a meniscus shape, having both surfaces of aspheric shape, having an image-side surface that is concave on the optical axis, and being made of plastic. The single focus wide-angle lens may include only three lens elements. Specified on-axis conditions are satisfied in order to reduce aberrations and to make the single focus wide-angle lens compact. Additionally, satisfying a condition related to the half-field angle at the maximum image height helps reduce aberrations.

Abstract: A three lens group zoom lens is provided and includes three lens groups of negative, positive, and positive in this order from an object side and varies a magnification by changing distances among respective lens groups. A first group includes, in order from the object side, a negative lens in a meniscus shape directing a convex surface on the object side, a negative lens in a meniscus shape directing a convex surface on the object side, and a positive lens in a meniscus shape directing a convex surface on the object side. A second group includes, in order from the object side, a cemented lens including a bi-convex lens and a bi-concave lens, and a lens in a meniscus shape directing a concave surface on the object side. A third group includes a positive lens. Each of the first group and the second group includes an aspherical surface.