Abstract: A wide field optically athermalized orthoscopic lens system includes, in order from object to image, a first lens having a negative power, a second lens having a positive power, a third lens group having a positive power, a fourth lens having a positive power and a fifth lens having a negative power. The third lens group includes two lenses having, in order, a first lens with positive power and a second lens with negative power. The powers, shapes, Abbe dispersion values and temperature coefficients of refractive indices of the lenses are selected such that the lens system is athermalized, orthoscopic and achromatized over a wide (e.g. >140° C.) temperature range.

Abstract: An endoscope objective lens unit includes a front lens group and a rear lens group with a diaphragm interposed therebetween. The front lens group includes a first lens and a second lens, and the rear lens group includes a third lens, a fourth lens and a fifth lens. The endoscope objective lens unit satisfies following expressions (1A) to (4): (1A) ?3<SF??1; (2) ?3<Fr/Ff<?1.1; (3) ?1.6<Ff/f<?0.6; and (4) Ff/f1<1.6, where SF is a shape factor, Ff is a focal length of the front lens group, Fr is a focal length of the rear lens group, f is a focal length of the entire unit, and f1 is a focal length of the first lens.

Abstract: An imaging lens is provided and includes: in order from the object side, a negative first lens, a negative second lens, a positive third lens, a stop, and a positive fourth lens. In the lens, each of the second lens, the third lens, and the fourth lens has at least one aspheric surface, and an Abbe number of a material of the third lens at the d-line is 35 or less. In addition, the imaging lens satisfies the following Conditional Expression (1): ?0.2<(R3+R4)/(R3?R4)<0.2 ??(1) where R3 is a paraxial radius of curvature of the object side surface of the second lens, and R4 is a paraxial radius of curvature of the image side surface of the second lens.

Abstract: A photographic lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a stop, and a third lens unit having a positive refractive power. In the photographic lens, the third lens unit moves towards the object side while the second lens unit moves towards the image side during focusing from an infinitely distant object to a closest distance object. In addition, in the photographic lens, an image forming magnification of the second lens unit during focusing on a closest distance object is appropriately set.

Abstract: A fisheye lens system and a photographing apparatus including the fisheye lens system. The fisheye lens system includes, in an order from an object to an image, a first lens group including at least three lenses and having negative refractive power; and a second lens group having positive refractive power, wherein the at least three lenses included in the first lens group include a first lens, a second lens, and a third lens, in the order from the object to the image.

Abstract: A lens system includes, in order from the subject side to the image side of thereof, a first lens group of negative refractive power, a second lends group of positive refractive power, and an image plane. The first lens group includes a first spherical lens, a second spherical lens, and a third spherical lens arranged in this order from the subject side to the image side of the lens system. The first spherical lens includes a first subject surface and a first image surface. The lens system satisfies the following formula: 8.9<D/F0<9.9, wherein, D is the distance between an apex point of the first subject surface and the image plane along the optical axis of the lens system, F0 is the effective focal length of the lens system.

Abstract: A projection lens system includes, from the magnified side to the reduced side thereof, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, and a field lens. The projection lens system satisfies the following conditions: 2.9<TT/f<3.7, and 1.85<f4/f<2.65, where TT is a total length of the projection lens system; f is an effective focal length of the projection lens system; f4 is an effective focal length of the field lens.

Abstract: A lens system includes a main lens and a transfer lens aligned with the main lens. The optical axis of the main lens is superposed on that of the transfer lens. The transfer lens includes, in order from the object side to the image side thereof, a first lens having negative refraction power, and a second lens having positive refraction power. The lens system satisfies the following conditions: 0.4<|f1/f2|<0.8; 2<v1/v2<3.8; 0.86<N1/N2<1.12; wherein, f1 is a focal length of the first lens, f2 is a focal length of the second lens, v1 is an Abbe constant of the first lens, v2 is an Abbe constant of the second lens, N1 is a refractive index of the first lens, N2 is a refractive index of the second lens.

Abstract: A relay lens is used for an imaging system having a main lens. The main lens has a pupil plane. The relay lens, in the order from the subject side to the image side thereof, includes a first lens of negative refractive power, and a second lens of positive refractive power. The first lens has a first principle plane and a second principle plane. The second lens has a third principle plane and a fourth principle plane. The relay lens system satisfies the following formulas: 0.53<|ƒ1/ƒ2|<0.57; 1.54<?1/?2<3.11; 0.22<D1/D2<0.65, where f1 and f2 are the effective focal lengths of the first and second lenses, v1 and v2 are the Abbe numbers of the first and second lenses, D1 is the distance between the second principle plane and the third principle plane, D2 is the distance between the fourth principle plane and the pupil plane.

Abstract: A super-wide-angle lens system for imaging an object on an imaging surface, includes a first lens group with negative refraction power and a second lens group with positive refraction power. The first lens group includes a first spherical lens with negative refraction power, a second spherical lens with negative refraction power, and a third spherical lens with positive refraction power. The first lens has a first surface facing the object side of the first lens group. The second lens group includes a fourth spherical lens with positive refraction power and a fifth spherical lens with negative refraction power. The system satisfies the formulas: 0.01<D/|FG1|<1, and 2<D/FG2<4, where D is the distance from the first surface to the imaging surface, FG1 is the effective focal length of the first lens group, and FG2 is the effective focal length of the second lens group.

Abstract: An electronic image pickup apparatus includes a zoom lens system which is a taking optical system, an electronic image pickup element which is disposed at an image side of the taking optical system (zoom lens system), and which converts an image formed by the taking optical system (zoom lens system) to an electric signal, and an image restoring section which restores electrically a photographed image according to a difference in occurrence of an aberration by the taking optical system (zoom lens system) in an air environment photography and in a underwater environment photography.

Abstract: A lens for projection substantially consists of a negative first-lens having a concave surface facing the reduction side, a positive second-lens having a convex surface facing the magnification side, a negative third-lens having a concave surface facing the magnification side, a positive fourth-lens having a convex surface facing the reduction side, and a positive fifth-lens, arranged in this order from the magnification side. Further, the following formulas (A) through (D) are satisfied: 1.2?Bf/f?2.5??(A); ?3.0?f3F/f??0.8??(B); 1.4?f5F/f5?8.5??(C); and 1.0?d12/f?2.7??(D), where Bf is a back focus, f is the focal length of an entire lens system, f3F is the focal length of a magnification-side surface of the third-lens, f5F is the focal length of a magnification-side surface of the fifth-lens, f5 is the focal length of the fifth-lens, and d12 is an air space between the first-lens and the second-lens.

Abstract: An imaging lens is provided and includes: in order from the object side, a negative first lens, a negative second lens, a positive third lens, a stop, and a positive fourth lens. In the lens, each of the second lens, the third lens, and the fourth lens has at least one aspheric surface, and an Abbe number of a material of the third lens at the d-line is 35 or less. In addition, the imaging lens satisfies the following Conditional Expression (1): ?0.2<(R3+R4)/(R3?R4)<0.2??(1) where R3 is a paraxial radius of curvature of the object side surface of the second lens, and R4 is a paraxial radius of curvature of the image side surface of the second lens.

Abstract: The present invention provides a wide-angle imaging lens assembly comprising, in order from an object side to an image side: a first lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a third lens element with positive refractive power; a fourth lens element with negative refractive power having a concave image-side surface; and a fifth lens element with positive refractive power; wherein the two lens elements with refractive power closest to the object side are the first lens element and the second lens element; and wherein the number of lens elements with refractive power does not exceed six.

Abstract: A retrofocus-type wide angle lens includes a first lens group having negative refractive power as a whole, a second lens group having positive refractive power as a whole, a stop, and a third lens group having positive refractive power as a whole, which are arranged in this order from the object side of the retrofocus-type wide angle lens. Further, the first lens group includes two negative meniscus lenses, each having a convex surface facing the object side. Further, each of the second lens group and the third lens group includes a three-element cemented lens.

Abstract: A super wide angle lens is a super wide angle lens which is of high-resolution and whose size, weight and cost can be reduced. It employs a four-group five-element constitution in which in the order from an object side, a meniscus single lens having a negative power, a single lens having a negative power, a single lens having a positive power, and a cemented lens having a positive power are included. The lenses excluding the meniscus single lens are plastic lenses and seven lens surfaces, that are a third surface, a fourth surface, a fifth surface, a sixth surface, a eighth surface, a ninth surface and a tenth surface, are aspheric.

Abstract: A wide angle lens whose field angle exceeds 160 degrees, includes a front group, an aperture stop, and a rear group arranged in this order from an object-side toward an image-side. The front group includes a first lens (negative meniscus) whose convex surface faces the object, a second lens (negative), a third lens (negative), and a fourth lens (positive), arranged in this order from the object-side toward the image-side. The rear group includes a fifth lens (positive), a sixth lens (negative), and a seventh lens (positive), arranged in this order from an aperture-side toward the image-side. The fifth and sixth lenses are combined, forming a cemented lens having positive refractive power. The fifth and sixth lenses are made of materials having Abbe numbers of greater than or equal to 50 and less than or equal to 30, respectively. A surface of the seventh lens facing the image is aspheric.

Abstract: An imaging lens is provided and includes: in order from an object side thereof, a first lens of a negative lens having a concave surface on an image side thereof and having at least one aspheric surface; a second lens of a positive lens having at least one aspheric surface; a stop; and a third lens of a positive lens having a convex surface on the image side thereof and at least one aspheric surface. The following Conditional Expressions (1) and (2) are satisfied. 1.5<vd3/vd2??(1) 0.0<|f1/f23|<0.5??(2) In which vd2 represents an Abbe number of the second lens at the d-line, vd3 represents an Abbe number of the third lens at the d-line, f1 represent a focal length of the first lens, and f23 represents a composite focal length of the second and third lenses.

Abstract: In constructing a lens for projection substantially consisting of seven lenses, and the reduction side of which is telecentric, a first-lens-group is composed of two lenses including at least one negative lens. A second-lens-group is composed of a positive second-group first-lens having a convex surface facing the magnification side, a negative second-group second-lens having a concave surface facing the magnification side, a positive second-group third-lens having a convex surface facing the reduction side, a positive second-group fourth-lens, and a positive second-group fifth-lens in this order from the magnification side. The formulas (A) and (B) are satisfied: 1.2?Bf/f?2.5??(A); and f23/f?1.5??(B), where Bf is a back focus in air of an entire lens system, f is the focal length of the entire lens system, and f23 is the focal length of an air lens between a reduction-side surface of the second-group second-lens and a magnification-side surface of the second-group third-lens.

Abstract: Disclosed are an imaging lens having a small size and high imaging performance, a camera module that is provided with the imaging lens and can obtain a high-resolution image signal, and an imaging apparatus. An imaging lens includes a first lens having a positive power, a second lens having a negative power, a third lens that has a positive power and includes a convex image-side surface, and a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis. The first to fourth lenses are arranged in this order from an object side, and the imaging lens satisfies Conditional expression.

Abstract: The wide-angle optical system of the invention comprises, in order from its object side, a first lens group having negative refracting power and a second lens group having positive refracting power. The second lens group comprises, in order from the object side, a first cemented doublet lens, an aperture stop, a second cemented doublet lens and a first double-convex lens. The widest separation among axial air separations except a back focus provides an axial space for receiving the aperture stop. The optical system is divided into the first lens group and the second lens group with the second widest air separation as a boundary. Focusing is implemented by letting the whole optical system out. The optical system satisfies Condition (1). 1.4?nd?1.8 ??(1) Here nd is the d-line refractive index of the first double-convex lens.

Abstract: A wide angle lens whose field angle exceeds 180 degrees includes a front group, a diaphragm, and a rear group arranged in this order from an object side toward an image side. The front group includes a first lens (negative meniscus lens) whose convex surface faces the object side, a second lens (negative lens), and a third lens (positive lens) that are arranged in this order from the object side toward the image side. The rear group includes a fourth lens (positive lens), a fifth lens (negative lens), and a sixth lens (positive lens) that are arranged in this order from a diaphragm side toward the image side. Accordingly, an imaging system including six separate lenses is formed. The third lens is made of a material having an Abbe number ?dL3 satisfying ?dL3<21. The fifth lens is made of a material having an Abbe number ?dL5 satisfying ?dL5<21.

Abstract: A wide-angle lens includes, in order from an object side, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. The first lens group includes at least one negative meniscus lens having a convex surface facing the object side. The second lens group includes, in order from the object side, a positive lens, a negative lens and a positive lens. Given conditional expressions are satisfied.

Abstract: An objective lens includes, in order from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, wherein the front group includes, in order from the object side, a first lens which is a negative meniscus lens with a convex surface turned to the object side and a second lens which is a negative lens with a concave surface turned to the object side; the rear group includes, in order from the object side, a positive third lens and a fourth lens made up of a positive lens and a negative lens cemented together, and the objective lens satisfies conditional expression (1) below: ?0.8<f_F/f_R<?0.3 . . . (1), where f_F is a focal length of the front group, and f_R is a focal length of the rear group.

Abstract: A wide-angle optical lens assembly comprises, in order from an object side to an image side: a first lens element with a negative refractive power having concave image-side surface, a second lens element with a positive refractive power, a third lens element with a positive refractive power, and a fourth lens element with a positive refractive power having convex image-side surface, at least one surface of the fourth lens element thereof being aspheric. By such arrangement, total track length and photosensitivity of the wide-angle optical lens assembly can be effectively reduced while retaining large field of view and superb image quality.

Abstract: An image-forming lens includes, from an object side to an image side in order: a first lens group; an aperture; and a second lens group with a positive refractive power, the first lens group including, from the object side in order: a first F lens group with a negative refractive power; and a first R lens group with a positive refractive power, the first F lens group including, from the object side in order: a first negative lens which has a surface on the image side having a large curvature; and a second negative lens which has a surface on the object side having a large curvature, and the first R lens group including: any one of a positive lens and a cemented lens with a positive refractive power as a whole, wherein a distance from a surface on a most object side of the first lens group to an image plane in a state of focusing on an object at infinity: L, and a maximum image height: Y? satisfy Conditional expression 1: 2.8<L/Y?<4.3.

Abstract: An imaging lens SL installed in a single-lens reflex digital camera includes, in order from an object side, a first lens group G1, and a second lens group G2 having positive refractive power. The first lens group G1 includes, in order from the object side, a first lens component L11 having a negative meniscus shape with a convex surface facing the object side, a second lens component L12 having a negative meniscus shape with a convex surface facing the object side, and a third lens component L13. The third lens component L13 includes a double concave lens to the most object side. The imaging lens SL includes at least six lens components or more, thereby providing a sufficiently fast imaging lens having excellent optical performance, which is a large aperture, single-focal-length, wide-angle lens having an aspherical surface.

Abstract: An optical system includes, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. In the optical system, an aperture stop is located closer to the reduction conjugate side than the first lens unit, one or more positive lenses are located closer to the reduction conjugate side than the aperture stop, and the one or more positive lenses include a P-th positive lens located closest to the reduction conjugate side. Various optical qualities may be appropriately set to effectively control chromatic aberration for the entire image plane, provide high optical performance, and achieve a wide angle of view.

Abstract: An imaging lens includes, in order from an object side, a positive first lens group, a stop, and a positive second lens group. The first lens group includes, in order from the object side, a first lens, which is a negative meniscus lens having a convex object-side surface, and a second lens having a positive power and including a convex image-side surface. The second lens group includes, in order from the object side, a third lens having a negative power and including a concave object-side surface, a fourth lens having a positive power and including a convex image-side surface, a fifth lens, which is a biconvex lens, and a sixth lens, which is a meniscus lens having a negative power and including a convex surface facing an image side. Each of the first to sixth lenses is a single spherical glass lens.

Abstract: A projection lens and a projection device using the same are provided. The projection device includes a projection lens and an optical element. The projection lens includes a first lens group and a second lens group from an image side sequentially. The first lens group has a negative refracting power, and the first lens group includes an aspherical lens surface. The second lens group has a positive refracting power. The first lens group has a first focal length f1, and the second lens group has a second focal length f2. The first focal length f1 and the second focal length f2 satisfy the following two conditions: 0.5<|f1/f2|<1.5, and ?35 mm<f1<?15 mm.

Abstract: This invention provides an optical photographing lens assembly comprising, in order from an object side to an image side: a first lens with negative refractive power having a concave image-side surface; a second lens with positive refractive power having a concave object-side surface and a convex image-side surface; a third lens with positive refractive power having a concave object-side surface and a convex image-side surface; a fourth lens with negative refractive power; and a fifth lens with positive refractive power; wherein the optical photographing lens assembly further comprises a stop disposed between the second and third lenses; and wherein the distance on the optical axis between the fourth and fifth lenses is T45, the focal length of the optical photographing lens assembly is f, the number of the lenses with refractive power is N, and they satisfy the relations: 0.10<(T45/f)*10<6.00, 5?N?6.

Abstract: A wide-angle lens comprising: an imaging lens system, including: a front lens group, an aperture, and a rear lens group, arranged in that order from an object side to an image side; wherein said front lens group comprises first and second lens elements, having negative power respectively, and a third lens that is a positive lens, arranged in that order from the object side to an aperture side; wherein said rear lens group comprises fourth and fifth lens elements, having positive power respectively, arranged in order from the aperture side to the image side; where an incident angle to an optical axis of the imaging lens system of a chief ray of a maximum angle of view passing through the aperture is ?I, the following Expression 1 is satisfied.

Abstract: An optical system includes, in order from an object side to an image side, a first lens unit, a stop, and a second lens unit. The first lens unit includes a first negative lens having a meniscus shape and a negative refractive power at a position closest to the object side and a negative lens Gn having a negative refractive power at a position closer to the image side than the first negative lens. The second lens unit includes a positive lens Gp having a positive refractive power. A material of each of the negative lens Gn and the positive lens Gp satisfies the following condition: ?gF?(?0.001682·?d+0.6438)?0.01 where “?d” denotes an Abbe number of a lens material and “?gF” denotes a relative partial dispersion with respect to g-line light and F-line light.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1/fT<0.5 2.3<|f1/fw<3.5, where f1 is a focal length of the first lens unit, fT is a focal length of the zoom lens at a telephoto end, and fw is a focal length of the zoom lens at a wide-angle end.

Abstract: A five-lens image lens system is revealed. The five-lens image lens system includes a first lens group with a negative power and a second lens group with a positive power. Along an optical axis in order from an object plane to an image plane, the first lens group includes a negative first lens and a negative second lens while at least one of optical surfaces of the first lens and the second lens is an aspherical optical surface. The second lens group includes a positive third lens, a positive fourth lens, and a negative fifth lens from the object plane to the image plane while an image-side lens surface of the positive fourth lens is glued with an object-side lens surface of the negative fifth lens.

Abstract: An imaging lens includes negative first lens, negative second lens having a concave surface facing the image side, positive third lens, aperture stop, positive fourth lens, and fifth lens having a concave surface facing the object side, which are arranged sequentially from the object side. At least one of second lens, fourth lens and fifth lens has at least an aspheric surface. The Abbe number of third lens and the Abbe number of fifth lens are less than or equal to 30, and the Abbe number of fourth lens is greater than or equal to 40. Further, the following formula (1) is satisfied: 1.0<(R3?R4)/(R3+R4) ??(1), where R3: the paraxial curvature radius of an object-side surface of second lens, and R4: the paraxial curvature radius of an image-side surface of second lens.

Abstract: An optical system includes a first lens unit, an aperture stop, and a second lens unit having a positive refractive power. In the optical system, the first lens unit includes at least one positive lens made of a material whose Abbe number (?dGP) and relative partial dispersion (?gFGP) satisfy a predetermined condition.

Abstract: Including: a front lens group Gf disposed to an object side of an aperture stop; and a rear lens group Gr disposed to an image side of the aperture stop; the front lens group including a sub-lens group Ga having negative refractive power, the sub-lens group Ga including, in order from the most object side, at least three negative lenses, at least one of the three negative lens being an aspherical negative meniscus lens, the aspherical negative meniscus lens having a shape that negative refractive power is getting smaller from the center to the periphery, a cemented lens constructed by a positive lens, a negative lens, and a positive lens being disposed to the image side of the sub-lens group Ga, and given conditional expressions being satisfied, thereby providing a wide-angle lens having high optical performance with a wide angle of view.

Abstract: A wide-angle imaging lens module includes a fixed aperture diaphragm, a first lens, a second lens, a third lens and a fourth lens arranged from an object side to an image side in a sequence of: the first lens of a negative refractive power with a meniscus shape, having a concave surface on the image side and at least one aspheric surface; the diaphragm; the second lens of a positive refractive power, having a convex surface on the object side and at least one aspheric surface; the third lens of a negative refractive power, having a concave surface on the image side and at least one aspheric surface; the fourth lens of a positive refractive power, having a convex surface on the object side and at least one aspheric surface.

Abstract: A wide-angle lens LN consists of, in order from an object side: a first lens group Gr1 having positive refractive power; and a second lens group Gr2 having positive refractive power; the second lens group Gr2 is movable toward the object side with fixing the first lens group Gr1, thereby carrying out focusing on a close object, and a given conditional expression is satisfied. Therefore, a wide-angle lens having high optical performance with suppressing variation in aberrations upon focusing in spite of being a large aperture, an imaging optical apparatus equipped therewith, and a digital equipment are provided.

Abstract: A ultra-wide angle objective lens comprising a first group having a first lens element having a convex object surface facing the object and a concave image surface facing the image plane, and a second aspheric lens element, the second aspheric lens element having a varying power that is negative at its vertex; and that increases positively with radial distance from the vertex. A second group has at least one lens element and a positive power. A third group has at least a first and a second lens element and a positive power. The ratio of the total track to the focal length satisfies the condition that TT/fo=<33 and the image height on a focal plane is h(?)>f*?, where h(?) is the image height formed by an off-axis chief ray having a field angle ?, and f is the effective focal length of the lens.

Abstract: The present disclosure relates to a projection lens. The projection lens includes, in order from the magnified end to the minified end thereof, a first lens of negative refraction power, a second lens of positive refraction power, a third lens of negative refraction power, a fourth lens of positive refraction power, and a fifth lens of positive refraction power. The forth lens and the third lens are bonded to integrally form a compound lens of negative refraction power. The projection lens satisfies the following condition: 0.4<R12/f<0.9. Wherein, R12 is a radius of curvature of the surface at the minified end of the first lens, f is an effective focal length of the projection lens.

Abstract: A micro prime lens system is provided. From an object side to an image side, the micro prime lens system sequentially includes a first lens, a second lens, a third lens and a fourth lens, which have a positive, a negative, a positive and a negative index of refraction, respectively. The third lens is an aspherical lens made of glass material and conforms to the following condition: 0.3<f3/f<1.5, wherein f3 represents a focal length of the third lens, and f represents a focal length of the micro prime lens system. The utilization of glass aspherical surfaces of the third lens effectively improves the aberration of the micro prime lens and successfully decreases the F number, and in other words to increase aperture diameter. Therefore, the luminous flux density is increased and the image resolution is raised.

Abstract: An imaging lens includes, sequentially from an object side, a first lens (L11) configured by a negative meniscus lens disposed with the convex surface on the object side; a second lens (L12) configured by a positive biconvex lens; a negative third lens (L13); and a fourth lens group (L14) configured by a positive meniscus lens disposed with the convex surface on the image plane IMG side. By satisfying given conditions, the imaging lens is able to control ghosting occurring between the last lens surface and the imaging element and ghosting caused by light reflected by the lens surface nearest the object, without sacrifice to the compact-size of the optical system or high optical performance.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1 |/fT<0.5, where f1 is a focal length of the first lens unit, and fT is a focal length of the zoom lens at a telephoto end.

Abstract: A compact fisheye objective lens comprising a series of six lens elements arranged on an optical axis to focus an image on an image plane, the compact fisheye objective lens having a first lens element with a convex object surface that faces the object and a concave image surface that faces image plane, and a second lens element spaced to the right of the first lens element concave image surface, the second lens element having a concave object surface and a concave image surface. The compact fisheye objective lens having singlet third and fourth lens elements, the fifth and sixth lens elements being combined to form a doublet having a positive power.

Abstract: An endoscope objective lens system design is disclosed, generally comprising a first lens group having overall negative refractive power, a second lens group having overall positive refractive power, and an aperture diaphragm disposed between the first and second lens groups wherein the first lens group includes a plano-concave lens with its concave surface facing the objective end of the endoscope.

Abstract: A front projection display device includes an optical engine including an illumination system, an imaging system, and projection optics. The projection optics include a first lens group of negative refractive power that has at least one aspheric surface. The projection optics output an image at a half field angle of at least 45°, where the image has substantially no distortion. For example, when the first lens group is placed at a distance of less than 1 meter from a viewing screen, the output image has a size of about 40 inches diagonal or greater, and requires substantially no keystone correction. In other aspects, the optical engine can be implemented in a wall-mounted projection system, a multimedia system, a compact integrated monitor system, and a portable projection unit.

Abstract: A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group is disposed between a magnified side and a reduced side and includes a first lens and a second lens arranged in sequence from the magnified side to the reduced side. The refractive powers of both the first lens and the second lens are negative, and the first lens is an aspheric lens. The second lens group is disposed between the first lens group and the reduced side and includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the magnified side to the reduced side. The refractive powers of the seven lenses from the third lens to the ninth lens are respectively positive, negative, positive, negative, positive, negative, and positive in sequence.

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.