Abstract: An inspection system including a catadioptric objective that facilitates dark-field inspection is provided. The objective includes an outer element furthest from the specimen having an outer element partial reflective surface oriented toward the specimen, an inner element nearest the specimen having a center lens comprising an inner element partial reflective surface oriented away from the specimen, and a central element positioned between the outer lens and the inner lens. At least one of the outer element, inner element, and central element has an aspheric surface. The inner element is spatially configured to facilitate dark-field inspection of the specimen.

Abstract: There is provided a projection optical system capable of projecting an image formed on an image forming unit on a projection plane, which has an extremely short projection distance and a small size.

Abstract: An optical imaging system for pickup, sequentially arranged from an object side to an image side, comprising: the first lens element with positive refractive power having a convex object-side surface, the second lens element with refractive power, the third lens element with refractive power, the fourth lens element with refractive power, the fifth lens element with refractive power; the sixth lens element made of plastic, the sixth lens with refractive power having a concave image-side surface with both being aspheric, and the image-side surface having at least one inflection point. By such arrangements, the optical imaging system for pickup satisfies conditions related to shorten the total length and to reduce the sensitivity for using in compact cameras and mobile phones with camera functionalities.

Abstract: This invention provides an optical lens system in order from an object side to an image side comprising: a first lens element having a convex object-side surface; a negative second lens element having a concave object-side surface and a convex image-side surface; a positive third lens element having a convex object-side surface and a convex image-side surface; a plastic negative fourth lens element having a concave object-side surface and a convex image-side surface, with both the object-side and image-side surfaces thereof being aspheric. By such arrangement, the incident angle of off-axis light projected onto the sensor can be suppressed for improving the sensitivity of the sensor effectively. Also, a sufficient back focal length can be retained for disposing other optical elements (e.g., an IR-pass filter), and thereby the system can be more suitable for the infrared aspect of optical imaging systems.

Abstract: An imaging lens composed of a positive first lens group, an aperture stop, a positive second lens group, and a positive third lens group disposed in order from the object side. The first lens group includes one negative lens and one positive lens disposed in order from the object side. The second lens group includes one negative lens and one positive lens, has at least one aspherical surface, and is composed of three lenses or less, in which the most object side surface and the most image side surface of the second lens group are concave and convex surfaces respectively. The third lens group is composed of a negative lens with a concave surface on the object side and one or more positive lenses disposed in order from the object side.

Abstract: An optical image collecting system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The second through sixth lens elements all have refractive power. The fifth lens element has a concave object-side surface and a convex image-side surface, wherein at least one of the object-side surface and the image-side surface of the fifth lens element is aspheric. The sixth lens element has a concave image-side surface at a paraxial region, wherein the image-side surface of the sixth lens element changes from concave at the paraxial region to convex at a peripheral region, and both of an object-side surface and the image-side surface of the sixth lens element are aspheric.

Abstract: A zoom lens including, in order from object side to image side: a first positive lens unit which does not move for zooming; a second negative lens unit which moves during zooming; a third positive lens unit which moves during zooming; a fourth lens unit which moves during zooming; and a fifth positive lens unit which does not move for zooming. The second unit passes through a point at which magnification of the second unit becomes ?1 during zooming from wide-angle end to telephoto end, and ?1<?34<?0.3, and 4.0<|m2/m3|<15 are satisfied where ?34 represents a magnification of a combined unit including the third and fourth units at a zoom position fz at which the magnification of the second unit becomes ?1, and m2 and m3 respectively represent displacements of the second and third units on optical axis at the zoom position fz with reference to the wide-angle end.

Abstract: An imaging-lens substantially consists of a first-lens-group, a stop and a second-lens-group in this order from object-side. The first-lens-group substantially consists of three or less lenses including a negative-lens arranged closest to object-side and a positive-lens arranged on image-side of the negative-lens. The first-lens-group includes a negative-lens having a meniscus-shape with its convex-surface facing object-side and a positive-lens cemented on the negative-lens in this order from object-side. The second-lens-group substantially consists of five or less lenses including a cemented-lens of two lenses of a positive-lens and a negative-lens and a single-lens having positive-refractive-power, and which is arranged on image-side of the cemented-lens.

Abstract: A wide angle lens system and an electronic apparatus including the same are provided. The wide angle lens system includes a first lens group having a negative refractive power, and a second lens group having a positive refractive power. The second lens group is spaced apart from the first lens group by a maximum air gap. The first lens group and the second lens group are sequentially arranged from an object side toward an image side. The second lens group includes a positive 2-1 lens group, a negative 2-2 lens group, and a positive 2-3 lens group, and focusing is performed by moving the 2-2 lens group along an optical axis.

Abstract: A junction type compound lens using glass and resin is used. By properly controlling the difference between refractive indices and the difference between Abbe numbers of the resin and glass, interface reflection that occurs when a ray with a large incidence angle is incident is restricted, and generation of a flare or a ghost image is restricted. Further, by properly controlling the difference in refractive index and the difference in Abbe number, various aberrations, such as spherical aberration, field curvature, and chromatic aberration, which may deteriorate optical performance, can be corrected. Thus, a small and high-performance imaging lens can be provided.

Abstract: A lens apparatus includes, in order from an object side: a first lens unit; an aperture stop; and a positive second lens unit. The first lens unit includes, in order from the object side, a first negative lens, a second negative lens having at least one aspheric surface, and a positive lens. The second lens unit includes at least one negative lens and at least two positive lenses. The first and second negative lenses of the first lens unit are meniscus lenses having a surface convex toward the object side. The focal length of the optical system, the focal lengths of the first and second lens units, the mean values of Abbe constants of the positive lens and the negative lenses of the first lens unit, and the mean values of Abbe constants of the positive lenses and the negative lenses of the second lens unit are appropriately configured.

Abstract: An imaging lens includes: a first lens group; an aperture stop; and a second lens group having a positive power, in this order from an object side. The first lens group includes a first lens having a negative power and a second lens having a positive power. The imaging lens satisfies Conditional Formulae (1), (2), and (3): ?0.50<f/f1<0.20??(1) 0.08<d12/f<0.35??(2) 2.5<TL/Y<4.0??(3) wherein f is the focal length of the entire system, f1 is the focal length of the first lens group, d12 is a distance along an optical axis from the image side lens surface of the first lens to the object side lens surface of the second lens, TL is the distance along the optical axis from the most object side lens surface within the first lens group to an imaging surface Sim, and Y is a maximum image height, when focused on an object at infinity.

Abstract: An optical unit includes a plurality of lenses arranged along an optical path from an object side toward an image side, the plurality of lenses including at least one lens including an image side surface and an object side surface, one of which is formed to be an aspheric surface at wafer level, the aspheric surface of the at least one lens being formed to serve as one of an aperture stop surface having an aperture stop function and a light-shielding surface having a light-shielding function.

Abstract: An optical image capturing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has refractive power. The third lens element has refractive power. The fourth lens element has refractive power. The fifth lens element with refractive power has both surfaces being aspheric. The sixth lens element with refractive power has both surfaces being aspheric. The seventh lens element with refractive power has both surfaces being aspheric. The optical image capturing system has a total of seven lens elements with refractive power and a stop disposed closer to the object side than the third lens element.

Abstract: An adjustable lens includes a first lens member having a first corrugated surface, a second lens member having a second corrugated surface, and blackout regions disposed between the first and second corrugated surfaces. The first corrugated surface includes a periodic structure of alternating ridge and groove sections. The second corrugated surface includes a periodic structure of alternating ridge and groove sections. The blackout regions are positioned to block image light passing through either the ridge sections of the first lens member, or alternatively, the groove sections of the first lens member.

Abstract: Disclosed herein is an imaging lens, including: a first lens having positive (+) power and being biconvex; a second lens having negative (?) power and being concave toward an image side; a third lens having positive (+) power and being biconvex; a fourth lens having positive (+) power and being convex toward the image side; and a fifth lens having negative (?) power and being concave toward the image side, wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are sequentially disposed from an object side.

Abstract: A first lens group having positive refractive power and a second lens group are arranged in this order from an object side, and only the first lens group moves in the optical axis direction while focusing. The first lens group substantially consists of a positive 1-1 lens, a positive 1-2 lens, a positive 1-3 lens, a negative 1-4 lens, an aperture stop, a negative 1-5 lens, a positive 1-6 lens, and a positive 1-7 lens. The 1-3 lens and the 1-4 lens are cemented to each other, and the 1-5 lens and the 1-6 lens are cemented to each other. The second lens group substantially consists of a negative 2-1 lens and a positive 2-2 lens. Only the first lens group moves in the optical axis direction while focusing.

Abstract: An imaging lens includes: a first lens group; an aperture stop; and a second lens group having a positive refractive power, in this order from an object side. The first lens group includes a negative first lens provided most toward the object side. The second lens group includes a positive lens, provided most toward an imaging surface, and a negative lens having a concave surface and an aspherical surface at least toward the object side. The following Conditional Formulae are satisfied: 0.03<(|Sagsp1|?|Sagas1|)/Re1<0.35; and 1.819?NdAB wherein Sagsp1 is the sag of a reference spherical surface at the edge of the effective diameter of the object side surface of the negative lens, Sagas1 is the sag of the aspherical surface of the lens, Re1 is the effective diameter of the object side surface of the lens, and NdAB is the average refractive index of the positive lens and the negative lens.

Abstract: An optical lens assembly for image taking includes a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element with positive refractive power includes a convex object-side surface at a paraxial region. The second lens element with negative refractive power includes a concave object-side surface at a paraxial region. The third lens element with refractive power includes a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region. The fourth lens element made of plastic with negative refractive power includes a concave object-side surface at a paraxial region and an image-side surface. At least one of the object-side surface and the image-side surface of the fourth lens element is aspheric, and the image-side surface of the fourth lens element is concave at a paraxial region and convex at a peripheral region.

Abstract: An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; and a fourth lens having negative refractive power, arranged from an object side to an image plane side. In the first lens, a curvature radius of an image-side surface is positive. In the second lens, curvature radii of the object-side surface and the image-side surface are both negative. In the third lens, a curvature radius of the object-side surface is positive and a curvature radius of the image-side surface is negative. When a whole lens system has a focal length f and the first lens has a focal length f1, the imaging lens satisfies the following conditional expression: ?3.0<f1/f<?1.

Abstract: An image lens assembly system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with negative refractive power has a convex object-side surface. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element has refractive power. The fifth lens element has refractive power. The sixth lens element with refractive power is made of plastic material, wherein at least one surface of the sixth lens element is aspheric. The seventh lens element with refractive power made of plastic material has a concave image-side surface changing from concave in a paraxial region to convex in a peripheral region, and at least one surface thereof is aspheric.

Abstract: A projection optical system which, when projecting an image of an optical modulator onto a projection surface on an enlarged scale, differs the aspect ratio of the image of the optical modulator and the aspect ratio of the image projected onto the projection surface, and includes, in order from the projection surface, a first group which is an enlargement optical system; a second group includes an adjustment optical component with a surface rotationally asymmetrical to an optical axis, when defining at least one direction of the vertical direction and the horizontal direction of the optical modulator as an adjustment direction in which conversion adjustment using compression or extension is performed, the adjustment optical component having at least one optical system which differs in power between the adjustment direction and another direction; and a third group which has a correction optical component with a surface rotationally symmetrical to the optical axis.

Abstract: An optical image capturing lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has positive refractive power, wherein an object-side surface and an image-side surface of the third lens element are aspheric. The fourth lens element with refractive power is made of plastic material and has a concave image-side surface, wherein an object-side surface and the image-side surface of the fourth lens element are aspheric, and the fourth lens element has at least one inflection point formed on at least one of the object-side surface and the image-side surface thereof.

Abstract: A low-cost imaging lens which corrects aberrations properly with a small F-value, ensures high performance with a larger number of constituent lenses and has a more low-profile design than before. The constituent lenses are arranged in the following order from an object side to an image side: a positive (refractive power) first lens having a convex object-side surface near an optical axis; a positive second lens having convex object-side and image-side surfaces near the optical axis; a negative third lens having a concave image-side surface near the optical axis; a fourth lens having at least one aspheric surface; a meniscus fifth lens having a concave object-side surface near the optical axis; a sixth lens as a double-sided aspheric lens; and a negative seventh lens as a double-sided aspheric lens having a concave image-side surface near the optical axis. These constituent lenses are not joined to each other.

Abstract: An image-capturing lens includes, in order from an object side: a meniscus-shaped first lens which has positive power near an optical axis; a second lens which has positive power near the optical axis and has negative power in the periphery of the second lens; and a meniscus-shaped third lens. The image-capturing lens satisfies the following conditional formulas: TL/f<1.10, 2.00<(r2+r1)/(r2?r1)<4.00, and 0.07<D2/f<0.19, where TL: the air-converted distance from the object-side surface of the first lens to the image-side surface thereof, f: the focal length of the entire system, r2: the radius of curvature of the first lens on the image side thereof, r1: the radius of curvature of the first lens on the object side thereof, D2: the distance between the first lens and the second lens.

Abstract: A photographing lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with positive refractive power has an object-side surface being convex at a paraxial region. The second lens element with negative refractive power has an object-side surface being concave at a paraxial region and an image-side surface being concave or planar at a paraxial region, wherein the second lens element is made of plastic material and the surfaces thereof are aspheric. The third lens element with negative refractive power has an object-side surface being concave at a paraxial region, and an image-side surface being concave at a paraxial region and being convex at a peripheral region, wherein the third lens element is made of plastic material, and the surfaces thereof are aspheric.

Abstract: A photographing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element with positive refractive power is made of plastic material and has a convex object-side surface and a convex image-side surface. The fourth lens element with negative refractive power is made of plastic material and has a concave object-side surface and a convex image-side surface. The fifth lens element with refractive power is made of plastic material and has a concave image-side surface, wherein the fifth lens element has at least one inflection point. The object-side surfaces and the image-side surfaces of the third through fifth lens elements are aspheric.

Abstract: The present invention provides a projection apparatus including an image generation device and a projection lens. The image generation device has a light valve, and generates a light. The projection lens includes a first lens group having an optical axis and a second lens group disposed between the first lens group and the light valve. The light generated from the light valve penetrates through the second lens group and forms an intermediate image between the first lens group and the second lens group. The intermediate image penetrates through the first lens group to form a projection image. A center of the projected image and a center of the light valve are disposed at a first side of the optical axis, and a center of the intermediate image is disposed at a second side of the optical axis different from the first side.

Abstract: A photographing lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with positive refractive power has an object-side surface being concave at a paraxial region thereof and an image-side surface being convex at a paraxial region thereof. The second lens element has positive refractive power. The third lens element with negative refractive power made of plastic material, and has an image-side surface being concave at a paraxial region thereof and being convex at a peripheral region thereof, wherein an object-side surface and the image-side surface of the third lens element are aspheric.

Abstract: An optical image capturing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with positive refractive power has a convex object-side surface. The second through seventh lens elements all have refractive power. The sixth lens element has an object-side surface and an image-side surface which are both aspheric. The seventh lens element has an object-side surface and an image-side surface which are both aspheric, its wherein the image-side surface of the seventh lens element changes from concave at a paraxial region thereof to convex at a peripheral region thereof.

Abstract: An imaging lens with large aperture ratio, high-performance and low-cost is provided, which is applied to an imaging element of a small-size and high resolution, in which aberration is corrected satisfactorily and sufficient diffraction resolution is achieved. An imaging lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence from an object side, wherein both surfaces of each lens are formed from aspheric surface, a diffraction optics surface exerting chromatic dispersion function is arranged on a surface on an image side of the second lens, each lens is configured from plastic material, and an aperture ratio is equal to or smaller than F/2.4.

Abstract: An imaging lens consists of seven lenses of a first lens that has positive refractive power in the vicinity of an optical axis and a convex surface facing an object side in the vicinity of the optical axis, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens having a concave surface facing an image side in the vicinity of the optical axis, and at least one of the surfaces of which includes an inflection point, and both of the surfaces of which are aspherical, which are in this order from the object side. Further, each of the first lens through the seventh lens is a single lens.

Abstract: The present invention relates to a surface light source, including a light source section made up of plural light emitting diodes and lenses that expand light from these light emitting diodes. The lens in the light source section has a light incident surface on which light from the light emitting diode is incident with an optical axis at a center, and a light exit surface that expands and emits the incident light. The light incident surface has a continued depressed surface, while the light exit surface has a continued projected surface.

Abstract: An image pickup lens 10 includes a first lens L1, a second lens L2, and a third lens L3. An image pickup surface I of a solid-state image sensor 51 is curved into the shape of a shallow concave spherical surface. By forming an image side surface 3b of the third lens L3, which is the lens nearest to the image side, into an aspherical shape, it is possible to make a curvature of field suitable to the curved image pickup surface I while securing excellent telecentric characteristics. The above image pickup lens 10 satisfies conditional expression (1) where THID is a thickness of an outermost periphery PA of the lens L3 nearest to the image side along an optical axis direction AX and THIC is a thickness of the lens L3 nearest to the image side on the optical axis AX.

Abstract: An image lens, in order from an object side to an image side thereof, includes a first lens including a first surface and a second surface, a second lens including a third surface and a fourth surface, a third lens including a fifth surface and a sixth surface, a fourth lens including a seventh surface and a eighth surface, and an image plane. The image lens satisfies the following formulas: D/TTL>1.11; D/L>1.13; Z/Y>0.076; wherein D is the maximum image diameter of the image plane; TTL is a total length of the image lens; L is a distance from an outermost edge of the eighth surface to an optical axis of the image lens; Z is a distance from a central point of the sixth surface to an outermost edge of the sixth surface; and Y is a distance from the outermost edge of the sixth surface to the optical axis.

Abstract: A projection lens includes a first lens group, a second lens group and a third lens group, all of which are arranged in sequence from an projection side to an image source side along an optical axis. The first lens group is with negative refractive power and includes four lenses. The second lens group is with positive refractive power and includes two lenses. The third lens group is with positive refractive power and includes a stop and six lenses.

Abstract: Systems and methods for inspection are provided utilizing a wide angle optical system. The optical system includes a wide angle input lens group and an output lens group. The wide angle input lens group is configured to receive wide-angle radiation, e.g., having an angular spread of 60 degrees or more, from an object surface, and produce imageable radiation. The wide angle input lens group is arranged such that no intermediate focused image is formed within or after the wide angle input lens group. The output lens group is configured to receive the imageable radiation from the wide angle input lens group and focus the imageable radiation onto an image plane to image at least part of the object surface. A detector receives the image of the at least part of the object surface and, based on the received image, detects, for example, contamination on the object surface.

Abstract: An image capturing optical lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element with positive refractive power has a convex image-side surface. The fourth lens element with refractive power has a concave object-side surface and a convex image-side surface. The fifth lens element with refractive power is made of plastic material, and has a concave image-side surface, wherein the fifth lens element has at least one inflection point formed on at least one of the surfaces thereof. The surfaces of the third lens element, fourth lens element and fifth lens element are aspheric.

Abstract: An imaging lens includes: a movable lens group with total positive refractive power, including first and second sub lens groups; and an ever-fixed lens group that is ever-fixed. The imaging lens has first and second focusing modes for focusing operation in first and second focus ranges, respectively. The first focus range covers from an object at an infinite distance to an object at a first finite distance, and the second focus range covers from an object at a second finite distance shorter than the infinite distance to an object at a third finite distance shorter than the first finite distance. The first sub lens group is configured to be fixed and the second sub lens group is configured to travel, during each of the first and second focusing modes. Traveling of the movable lens group toward object plane allows switching from the first to second focusing modes.

Abstract: An imaging lens includes: a movable lens group configured to travel to allow the imaging lens to come into focus; and a rearmost lens group arranged at a most-image-sided fixed position, and having negative refractive power. Following conditional expression is satisfied, ?2<ft/fr<?0.45??(1) where ft is a total focal length of the imaging lens in a condition that the imaging lens is in focus on an object at infinite, and fr is a focal length of the rearmost lens group.

Abstract: A wide-angle lens system is formed, sequentially from an object side, with a first group having a positive power, a second group having a negative power and a third group having a positive power, and at the time of focusing, only the second group is moved on an optical axis. The lens system satisfies conditional formulas of 0.3<BH1/T1<0.7 and 0.9<f3/f<1.8 (where BH1 is a distance from the final surface of the first group to a principal point position on the back side of the first group, T1 is a distance on the optical axis from a lens element surface of the first group closest to the side of the object to a lens element surface closest to the side of the image, f3 is the focal length of the third group and f is the focal length of the entire system).

Abstract: A projection lens configured to form an image from an image source which is disposed at an object side is provided. The projection lens includes a lens group and an aspheric mirror. The lens group has a first optical axis, and an intermediate image is formed by the lens group from the image source. The aspheric mirror has a second optical axis and an aspheric surface. The lens group is disposed between the object side and the aspheric mirror. The aspheric surface faces the lens group and reflects the intermediate image to form the image at an image side. The first optical axis is not coaxial with the second optical axis, and an offset of the image relative to the first optical axis is larger than or equal to 100%.

Abstract: A first lens group including two aspherical lenses, a second lens group consisting of three negative meniscus lenses, each negative meniscus lens having a convex surface facing the enlargement side, a third lens group having a negative refractive power and including at least one cemented lens, and a fourth lens group having a positive refractive power and including at least two cemented lenses and one aspherical lens are arranged in this order from the enlargement side. Predetermined conditional expressions are satisfied.

Abstract: An image lens assembly system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with negative refractive power has a convex object-side surface. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element has refractive power. The fifth lens element has refractive power. The sixth lens element with positive refractive power is made of plastic material, wherein at least one surface of the sixth lens element is aspheric. The seventh lens element with negative refractive power made of plastic material has a concave image-side surface changing from concave at a paraxial region to convex at a peripheral region, and at least one surface thereof is aspheric.

Abstract: An imaging lens having reduced susceptibility to thermally-induced stress birefringence for imaging an object plane to an image plane; comprising: an aperture stop positioned between the object plane and the image plane; a first group of lens elements located on the object plane side of the aperture stop; and a second group of lens elements located on the image plane side of the aperture stop; wherein the lens elements immediately adjacent to the aperture stop are fabricated using glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; and wherein the other lens elements in the first or second groups of lens elements are fabricated using glasses having at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.

Abstract: An imaging lens having reduced susceptibility to thermally-induced stress birefringence for imaging an object plane to an image plane; comprising a plurality of lens elements. The lens element that experiences a highest optical power density is fabricated using a glass having a negligible susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric.

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 internal focus lens comprising sequentially from an object side a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The second lens group is configured by a simple lens element and is moved along an optical axis to perform focusing. The internal focus lens satisfies condition expressions (1) 0.48<|f3|/f<0.73 and (2) 1.05<Fno×f1/f<1.42, where f3 is the focal length of the third lens group, f is the focal length of the entire optical system, f1 is the focal length of the first lens group, and Fno is the F number of the entire optical system.

Abstract: A photographing lens and a photographing apparatus including the photographing lens. The photographing lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are arranged sequentially from an object side. The first lens has a concave surface toward the object side and has a positive refractive power, and the second lens is formed with a meniscus shape having a concave surface toward an image side and has a negative refractive power.

Abstract: An optical image capturing system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with positive refractive power has a convex object-side surface. The second through seventh lens elements all have refractive power. The sixth lens element has an object-side surface and an image-side surface which are both aspheric. The seventh lens element has an object-side surface and an image-side surface which are both aspheric, its wherein the image-side surface of the seventh lens element changes from concave at a paraxial region thereof to convex at a peripheral region thereof.