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: An optical receptacle includes an optical fiber attaching section, a photoelectric conversion device, and a lens, the lens includes a first face that faces an end portion of an optical fiber and is composed of a concave face that recesses towards a light-receiving element side, and a second face that faces the light-receiving element and is composed of a convex face that projects towards the light-receiving element side, and as a result of the combination of the concave face and the convex face, is formed such that outgoing light from the optical fiber that is attached at an angle to an optical axis of the lens is collected in an appropriate area of the light-emitting element.

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 first lens having a convex object-side surface near an optical axis; a second lens having a convex object-side surface near the optical axis; a third lens having at least one aspheric surface; a fourth lens having at least one aspheric surface; a fifth lens as a double-sided aspheric lens; a sixth lens as a double-sided aspheric lens having a concave image-side surface near the optical axis; and a 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: 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 first lens having a convex object-side surface near an optical axis; a positive second lens; a negative third lens having a convex object-side surface near the optical axis; a fourth lens having at least one aspheric surface; a fifth lens as a double-sided aspheric lens; a sixth lens as a double-sided aspheric lens; and a 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 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 luminous flux limit device, an optical scanning unit employing the luminous flux limit device, and an electrophotographic image forming apparatus are provided. The luminous flux limit device limits a luminous flux of the optical scanning unit and includes a light-blocking portion, a light transmissive region around the light blocking region, and a light blocking outer region around the light transmissive region.

Abstract: An optical assembly is provided wherein the optical assembly includes a first optical element and a second optical element. The first optical element is configured to receive light and alter a transmission path of the light through the first optical element in a first direction and a second direction. The second optical element is configured to receive the light from the first optical element, and alter a transmission path of the light through the second optical element in the first and second directions. The light is passed through the second optical element, such that a sensor receives light from a field of view that is approximately 30 degrees to 60 degrees offset from a field of view of the sensor.

Abstract: Present embodiments provide for a mobile device and an optical imaging lens thereof. The optical imaging lens comprises an aperture stop and six lens elements positioned sequentially from an object side to an image side. Through controlling the convex or concave shape of the surfaces of the lens elements and designing parameters satisfying at least one inequality, the optical imaging lens shows better optical characteristics and the total length of the optical imaging lens is shortened.

Abstract: Systems and methods for implementing array cameras configured to perform super-resolution processing to generate higher resolution super-resolved images using a plurality of captured images and lens stack arrays that can be utilized in array cameras are disclosed. An imaging device in accordance with one embodiment of the invention includes at least one imager array, and each imager in the array comprises a plurality of light sensing elements and a lens stack including at least one lens surface, where the lens stack is configured to form an image on the light sensing elements, control circuitry configured to capture images formed on the light sensing elements of each of the imagers, and a super-resolution processing module configured to generate at least one higher resolution super-resolved image using a plurality of the captured images.

Abstract: An objective lens capable of converging light of a used wavelength with a satisfactory aberration on a recording medium is provided. An objective lens for converging light of a predetermined wavelength ? on a recording medium satisfies the following condition: |CML|+|CMF|<0.03 ?, where CML is an amount of a generated third-order coma aberration per 1 degree of tilt of the objective lens, and CMF is an amount of a generated third-order coma aberration per 1 degree of tilt of off-axis light.

Abstract: In one aspect, a light-mixing optic is disclosed for use with one or more light sources such as light emitting diodes. In one embodiment, an exemplary optic can include an optical body disposed about an optical axis and having an input and an output surface and a peripheral surface extending between the two. The input surface can form a central cavity for receiving light from the light sources, if not the light sources themselves. Further, the input surface can be shaped to refract substantially all of the light received from the one or more light sources away from the optical axis to the peripheral surface of the optic, where that light (e.g., substantially all of it) can be redirected (e.g., via total internal reflection or specular reflection) to the output surface. An array of micro-lenses or other surface features can be formed on the output surface. Further embodiments, as well as exemplary design methods, are also disclosed.

Abstract: An imaging lens includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a third lens group having negative refractive power, arranged in this order from an object side to an image plane side. The first lens group includes a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power. The second lens group includes a fourth lens and a fifth lens. The third lens group includes a sixth lens and a seventh lens. The fourth lens is formed in a shape so that a surface on the object side thereof has a negative curvature radius. The fifth lens is formed in a shape so that a surface on the image plane side thereof has a positive curvature radius. The first to third lenses have specific Abbe's numbers.

Abstract: An optical device where an image of an object is formed on an image pickup element and where an image restoration process is performed on the image obtained by the image pickup element, comprising a MTF that satisfies the following conditional expression (1): 0.001<L×NA<0.5,5<a<30??(1) where L: the width of the MTF when the MTF is a %, and NA: a numerical aperture of the optical device.

Abstract: An imaging lens system includes, sequentially from an object side to an image side: a first lens having a positive refractive power; a second lens having a negative refractive power; and a third lens having a positive refractive power or a negative refractive power, wherein a viewing angle ? satisfies following condition, 0.7<|tan ?|<1.5.

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: An imaging lens which uses a larger number of constituent lenses for higher performance and features a low F-value, low-profile design and a wide field of view. Designed for a solid-state image sensor, the imaging lens includes constituent lenses arranged in order from an object side to an image side: a first positive refractive power lens having a convex object-side surface; a second negative refractive power lens having a concave image-side surface; a third positive refractive power lens having a convex image-side surface; a fourth negative refractive power lens having a concave image-side surface; a fifth positive refractive power lens as a meniscus lens having a convex image-side surface; a sixth lens as a meniscus double-sided aspheric lens having a concave image-side surface near an optical axis; and a seventh negative refractive power lens as a double-sided aspheric lens having a concave image-side surface near the optical axis.

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: In a method for converting a light beam to a line focus, wherein the line focus extends according to its length along a first direction (y) and is narrow in a second direction (x) perpendicular to the first direction (y), the light beam is directed onto at least one conical optically operative surface, by which it is converted to the line focus. The light beam is directed onto the at least one optically operative surface with a ring-segment-shaped cross section transversely with respect to the light propagation direction. A device, in particular for carrying out the method, and an optical arrangement for generating a light beam with a ring-segment-shaped cross section are likewise described. In accordance with a further method and a further device, a line focus is generated only with spherical and/or cylindrical elements.

Abstract: A lens for projection which is used in an image display device which includes an image display element and projects and displays an image displayed on an image display surface of the image display element as a projection image on a projected surface in an enlarged manner, the lens for projection including in order from an enlargement side to a reduction side, a first lens group which is constituted of at least eight lenses and has a positive refractive power; an aperture; and a second lens group which is constituted of less than or equal to four lenses and has a positive refractive power, wherein the first lens group includes one or more aspherical lenses, and the one or at least one aspherical lens included in the first lens group has a largest thickness at a most peripheral portion of the lens.

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: 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 Formula 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: A method for providing an optical element may include providing an optical feature in the optical element that spreads or distributes light passing through the optical element. The method may also include providing a texturing in at least a portion of the optical feature of the optical element.

Abstract: An imaging lens formed of 4 lenses, in which a negative first lens having a meniscus shape with a convex surface on the object side, a biconvex positive second lens, a negative third lens having a concave surface on the image side, and a positive fourth lens having a convex surface on the object side, arranged in order from the object side, and the imaging lens satisfies conditional expressions (1): L12/f<0.82; (2): 2.3<L12×R2F2/f2<10.0; (5): ?1.3<f1/f<?0.9; and (6): 48<v1 simultaneously, where, L12 is the air equivalent distance between the first lens and the second lens, f is the focal length of the entire lens system, R2F is the radius of curvature of the object side lens surface of the second lens, f1 is the focal length of the first lens, and v1 is the Abbe number of the first lens with respect to the d-line.

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: 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.

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 has refractive power. 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, and has at least one surface being aspheric. The seventh lens element with refractive power is made of plastic material and has a concave image-side surface, wherein the image-side surface thereof changes from concave in a paraxial region thereof to convex in a peripheral region thereof, and at least one surface thereof is aspheric.

Abstract: A lens module may include a first lens having positive refractive power, a second lens having refractive power, a third lens having positive refractive power, a fourth lens having refractive power, a fifth lens having refractive power, a sixth lens having refractive power, and a seventh lens having negative refractive power. An inflection point may be formed on an image-side surface of the sixth lens. A turning point may be formed on an image-side surface of the seventh lens. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are disposed in a sequential order from the first lens to the seventh lens.

Abstract: An exemplary video wall includes two display panels and a polygonal mullion elimination lens. Each of the display panels includes a main body and a bezel surrounding the main body. The polygonal mullion elimination lens includes a central first concave surface configured to reflect internal light incident thereon, two flat surfaces respectively attached to the main bodies of the display panels, a central second concave surface opposite to the first concave surface, and two lateral surfaces each connecting between a corresponding one of the flat surfaces and the second concave surface. Portions of light emitted by the main bodies of the display panels can enter the mullion elimination lens via the flat surfaces.

Abstract: Provided is an optical system having, in order from an object, a positive first lens group (G1), an aperture stop (S) and a second lens group (G2), wherein the first lens group (G1) includes, in order from the object, a negative lens component (L1), a positive lens component (L2) and a first lens component (L3, L4), the image side surface of which is a concave surface facing the aperture stop (S), the second lens group (G2) includes, in order from the object, a second lens component (L5, L6), the object side surface of which is a concave surface facing the aperture stop (S), and a positive lens component (L8) disposed closest to the image, the first lens component (L1) and the second lens component (L2) face each other sandwiching the aperture stop (S), and the following conditional expressions (1) and (2) are satisfied: 1.5<fG1/f<2.6 . . . (1) and 2.1<TL/f<3.1 . . .

Abstract: Provided is an optical system having, in order from an Object, a first lens group (G1) having negative refractive power and a second lens group (G2), wherein the first lens group (G1) includes, in order from the object, a first negative lens (L11) and a second negative lens (L12) having a concave surface facing the object, and the following conditional expression (1) is satisfied: 7.94?(?fn12)/f<48.00??(1) where fn12 denotes a focal length of the second negative lens (L12), and f denotes a focal length of the entire optical system.

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 particle counter system is disclosed having a linear diverging lens, preferably a Powell lens, in order to create a top-hat profile without a loss of beam energy. The particle counter system disclosed creates ideal beam intensity distribution across the ribbon of light originating from the laser diode of the particle counter.

Abstract: An imaging lens which uses a larger number of constituent lenses for higher performance and features compactness and a wide field of view. The imaging lens is composed of seven lenses to form an image of an object on a solid-state image sensor. The constituent lenses are arranged in the following order from an object side to an image side: a first lens with positive refractive power; a second lens with positive or negative refractive power; a third lens with negative refractive power; a fourth lens with positive or negative refractive power as a double-sided aspheric lens; a meniscus fifth lens having a convex surface on the image side; a sixth lens with positive or negative refractive power as a double-sided aspheric lens; and a seventh lens with negative refractive power, in which an air gap is provided between lenses.

Abstract: An image-capturing lens is disclosed in the disclosure. The image-capturing lens includes a central portion and a periphery portion. The central portion includes a plurality of optical elements arranged in a circular fashion, and each of the optical elements differs in thickness. The periphery portion extends peripherally from the central portion and has a constant thickness. The thickness of the periphery portion is smaller than a thickness of one of the plurality of optical elements that is approximate to the periphery portion.

Abstract: The present invention discloses an LED lens and a light source device using the same. The light source device includes the LED lens and a LED. The LED lens comprises a light incident surface, a light emitting surface, and a bottom surface. The light emitting surface includes a recession portion disposed at the central thereof and a convex portion connected to the recession portion. The light incident surface is a concave surface and comprises a first optically active area and a second optically active area. The first optically active area is disposed at the central of the light incident surface; the second optically active area is connected to the first optically active area and the bottom surface. At the junction between the first optically active area and the second optically active area, it is an optical path inversion point that is disposed satisfying specific condition.

Abstract: An optical imaging lens includes, in order from an object side to an image side, first, second, third, fourth, fifth, sixth, and seventh lens elements arranged along an optical axis. The object-side surface of the first lens element has a convex portion and the image-side surface has a concave portion. The image-side of the third lens element is a concave surface. The object-side surface of the fourth lens element has a concave portion and the image-side surface of the fourth lens element has a convex portion. The image-side surface of the sixth lens element has a convex portion. The object-side surface of the seventh lens element has a convex portion and the image-side surface has a convex portion. The optical imaging lens only has seven lens elements having a 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, the second and the third lens elements all have refractive power. The fourth lens element with refractive power has both surfaces being aspheric. The fifth lens element with refractive power has both surfaces being aspheric. The sixth lens element with refractive power has an image-side surface having at least one convex shape at a peripheral region thereof and both surfaces being aspheric. The seventh lens element with refractive power has an image-side surface having at least one convex shape at a peripheral region thereof, wherein both surfaces being aspheric, and at least one surface has at least one inflection point thereon.

Abstract: A lens for projection substantially consists of a negative first lens group, a positive second lens group and a positive third lens group in this order from a magnification side. A reduction side is telecentric, and a most magnification-side lens is an aspheric plastic lens. The third lens group consists of a negative front group and a positive rear group in this order from the magnification side with an air space therebetween. The front group consists of a negative lens and a positive lens in this order from the magnification side with an air space therebetween, and the air space being narrower than the air space between the front group and the rear group. Conditional formula (1): ?0.7<fFG3/f<0.7 about front focus fFG3 of the third lens group and focal length f of an entire system is satisfied.

Abstract: The imaging lens system includes a first lens group and a second lens group that are sequentially arranged from an object side to an image side. The first lens group has a negative refractive power and includes a first lens having an image-side surface concave toward the image side. The second lens group includes a lens that is closest to the object side and an aspheric lens that is closest to the image side. The lens that is closest to the object side has a positive refractive power and an object-side surface convex toward the object side. The aspheric lens that is closest to the image side has a positive or negative refractive power and at least one inflection point on an image-side surface thereof.

Abstract: An imaging lens includes a first lens; a second lens; and a third lens arranged from an object side to an image plane side. The first lens has an object-side surface with a positive curvature radius. The second lens has an object-side surface and an image plane-side surface with negative curvature radii. The third lens has an object-side surface and an image plane-side surface with positive curvature radii. The object-side surface and the image plane-side surface of the third lens are respectively formed as an aspheric shape having an inflexion point. When the whole lens system has a focal length f, the first lens has a focal length f1, the second lens has a focal length f2, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions: f1<f2 1.0<f1/f<1.5 0.7<f2/f3<1.2.

Abstract: An imaging lens substantially includes seven lenses, constituted by: a first lens having a positive refractive power and a convex surface toward an image side; a second lens having a negative refractive power; a third lens having a positive refractive power; a fourth lens; a fifth lens having a positive refractive power; a sixth lens; and a seventh lens having a negative refractive power, a concave surface toward an image side, and at least one inflection point in the surface toward the image side; provided in this order from an object side. All of the first lens through the seventh lens are single lenses.

Abstract: An objective lens capable of converging light of a used wavelength with a satisfactory aberration on a recording medium is provided. An objective lens for converging light of a predetermined wavelength ? on a recording medium satisfies the following condition: |CML|+|CMF|<0.03?, where CML is an amount of a generated third-order coma aberration per 1 degree of tilt of the objective lens, and CMF is an amount of a generated third-order coma aberration per 1 degree of tilt of off-axis light.

Abstract: An imaging optical device includes a first lens group, which includes a first lens sub-group and a second lens sub-group that are physically connected without intermediate substance nor air existed therebetween and disposed in an order from an object side to an image side. The first lens sub-group has a positive refractive power, and the second lens sub-group has a negative refractive power.

Abstract: An imaging lens which uses a larger number of constituent lenses for higher performance and features a low F-value, low-profile design and a wide field of view. Designed for a solid-state image sensor, the imaging lens includes constituent lenses arranged in order from an object side to an image side: a first positive refractive power lens having a convex object-side surface; a second negative refractive power lens having a concave image-side surface; a third positive refractive power lens having a convex image-side surface; a fourth negative refractive power lens having a concave image-side surface; a fifth positive refractive power lens as a meniscus lens having a convex image-side surface; a sixth lens as a meniscus double-sided aspheric lens having a concave image-side surface near an optical axis; and a seventh negative refractive power lens as a double-sided aspheric lens having a concave image-side surface near the optical axis.

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: The imaging lens substantially consists of a first lens group having positive refractive power, an aperture stop, and a second lens group having positive refractive power, in this order from the object side. The first lens group consists of, in this order from the object side, an eleventh lens group and a twelfth lens group with a largest air space therebetween. The eleventh lens group has at least one negative lens with a concave surface toward the image side, having negative refractive power; and the twelfth lens group has positive refractive power. The second lens group substantially consists of, in this order from the object side, an aspheric lens having at least one aspheric surface, a positive lens, a negative lens, and a three-cemented lens formed by cementing a positive lens, a negative lens, and a positive lens in this order from the object side.

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: A photographic wide-angle lens system with internal focusing has a front array (II) of negative refractive power that is rigid within itself and fixed on the object-side, a rear array (III) of positive refractive power that is rigid within itself and fixed on the image side of an aperture diaphragm (A), and a focusing array (II) of positive refractive power having an optical single element (5) that is arranged between the front array (I) and the aperture diaphragm A and is axially movable from a maximum axial position on the object side to a maximum axial position on the image side to vary the focus distance from its maximum to its minimum value. The optical single element of the focusing array (II) has at least one aspheric surface (51, 52) and the image-side end lens (9) of the rear array (III) is configured as a positive, aspheric meniscus lens.

Abstract: An image-reading lens includes front-group and rear-group lens systems which are arranged on an object side and an image side, respectively. The front-group lens system includes equal to or less than 5 lenses which include at least one positive lens and at least one negative lens, and the rear-group lens system includes one negative lens. An angle of view of an entire system of the image-reading lens is equal to or more than 56°. The front-group and rear-group lens systems are structured such that with respect to a change in a distance between the front-group and rear-group lens systems, a change in a focal length of the entire system of the image-reading lens is small, and a change in an image plane is large, and by adjusting the distance between the front-group and rear-group lens systems, a required lens performance is obtained.

Abstract: Optical camera systems for nondestructive internal inspection of online, operating power generation turbines, including gas turbine combustor and turbine sections that are at high operating temperatures in the range of over 600° C. (1112° F.) and which include combustion gas contaminants. The inspection system includes one or more aspheric lenses capable of withstanding continuous operating temperatures above 600° C. The aspheric lenses, alone or in combination with spherical lenses, establish a wider field of view, and require fewer lenses in combination than lens mounts incorporating only spherical lenses. A cooling system incorporated in the inspection system facilitates continuous operation and inhibits lens external surface fouling from combustion gasses.