Abstract: A compact imaging lens system includes three lenses. The first lens is a positive meniscus lens having a convex side facing toward the image side, which has a big focusing power and is provided to capture image and for balance of aberration. The first lens serves to make the lens system a low sensitivity lens system. The second lens is a negative lens and is provided mainly for correcting chromatic aberration and off-axis aberration. An aperture is set between the first and second lenses, and this is of benefit to balance of aberration. The third lens is a negative lens and is provided for correcting off axis aberration. All the lenses can be made of plastics. This facilitates cost reduction, weight reduction, while still maintains a high resolution.

Abstract: A compact imaging lens system includes three lenses. The first lens is a positive meniscus lens having a convex side facing toward the image side, which has a big focusing power and is provided to capture image and for balance of aberration. The first lens serves to make the lens system a low sensitivity lens system. The second lens is a negative lens and is provided mainly for correcting chromatic aberration and off-axis aberration. An aperture is set between the first and second lenses, and this is of benefit to balance of aberration. The third lens is a negative lens and is provided for correcting off axis aberration. All the lenses can be made of plastics. This facilitates cost reduction, weight reduction, while still maintains a high resolution.

Abstract: A compact imaging lens system includes, in order from the object side to the image side, a first lens (1) of negative refractive power, a free-form surface prism (2) of positive refractive power and a second lens (3) of positive refractive power. The free-form surface prism has an incidence surface (S3), a reflection surface (S4) and an exit surface (S5). The first lens is disposed on the side of the incidence surface, and the second lens is disposed on the side of the exit surface. The free-form surface prism functions equivalent to a right-angle prism with aspheric surfaces.

Abstract: A microscope optical system includes, in order from an object side to an image side, a first lens group, a second lens group, a stop, a third lens group, a fourth lens group and a sensor. The first to fourth lens groups all have at least one lens element and at least one of lens elements of the first to fourth lens groups has an aspheric surface. The microscope optical system satisfies several specific conditions so as to provide microscope images of high resolution and high zoom ratio. A digital microscope having the microscope optical system adopts a CCD sensor so that a observer may observe microscope images displayed on a large display screen and store the images for subsequent edition or inspection.

Abstract: A zoom lens system includes, in order from an object side to an image side, a first positive lens group (G1), a second negative lens group (G2), a third positive lens group (G3), and a fourth positive lens group (G4). The second and third lens groups are movable for varying the focal length. The zoom lens system offers a four-times zoom ratio, and employs two plastic aspheric lenses (L3, L9) and a resin hybrid lens (L6). The first lens group consists of two lenses (L1, L2) arranged in an abutting relationship. The second and third lens groups each includes a pair of cemented lenses (L4, L5; L7, L8).

Abstract: A telescope includes an objective lens to receive an optical signal from an object and an electronic signal generator that generates an electronic signal representing for example distance and direction of the object. Both signals travel through a magnification system to from images on a viewer side image plane. The image representing the electronic signal is further transmitted, before reaching the image plane, through a reflector prism, by which the image of the electronic signal is maintained invariable with respect to the variation of magnification factor of the telescope.

Abstract: A compact wide-angle imaging lens system includes, in order from the object side to the image side, a first lens (1) of negative refractive power, a free-form surface prism (2) of positive refractive power, a second lens (3) of positive refractive power and a third lens (7) of negative refractive power. The free-form surface prism has an incidence surface (S3), a reflection surface (S4) and an exit surface (S5). The first lens and the free-form surface prism are arranged in a juxtaposed manner, and the second and third lenses are disposed below the free-form surface prism and adjacent to the image side. The free-form surface prism functions equivalent to a right-angle prism with aspheric surfaces.

Abstract: A microscope optical system includes, in order from an object side to an image side, a first lens group, a second lens group, a stop, a third lens group, a fourth lens group and a sensor. The first to fourth lens groups all have at least one lens element and at least one of lens elements of the first to fourth lens groups has an aspheric surface. The microscope optical system satisfies several specific conditions so as to provide microscope images of high resolution and high zoom ratio. A digital microscope having the microscope optical system adopts a CCD sensor so that a observer may observe microscope images displayed on a large display screen and store the images for subsequent edition or inspection.

Abstract: A compact zoom lens includes, from the object side to the image side, a negative first lens group (1), a positive second lens group (2) and a positive third lens group (3). The first lens group is stationary, and both the second and third lens groups are movable along the optical axis. The compact zoom lens is zoomed by varying the distance between the first and second lens groups, and the focal length is adjusted by varying the distance between the second and third lens groups. The zoom lens is composed of only four single lenses in three groups, of which three (10, 31, 32) are plastic aspheric lenses and one (20) is a glass spherical lens.

Abstract: A micro lens, from an object side to an image side, sequentially includes a stop, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power. The third and fourth lenses respectively comprise at least one aspherical surface. The negative refractive power gradually decreases from the center to the periphery of the fourth lens, and the refractive power of the periphery of the fourth lens is turned to positive. The relationship of the first lens and the focal length of the micro lens of the micro lens and the relationship of the third lens and the first lens satisfy the desired requirements, thus, to reduce the total length of the micro lens, tolerance sensitivity and cost.

Abstract: A fixed-focus lens system includes, in order from an object side to an image side along an optical axis thereof, an aperture stop, a first positive lens, a second negative lens, a third positive meniscus lens, and a fourth negative lens having increasing negative refractive power from the optical axis toward the periphery. The fixed-focus lens system satisfies the following condition: 0.1<RS32/f<0.3, where f is the effective focal length of the fixed-focus lens system, and RS32 is the curvature radius of an image-side surface of the third positive meniscus lens.

Abstract: A compact imaging lens system includes three lenses. The first lens is a positive meniscus lens having a convex side facing toward the image side, which has a big focusing power and is provided to capture image and for balance of aberration. The first lens serves to make the lens system a low sensitivity lens system. The second lens is a negative lens and is provided mainly for correcting chromatic aberration and off-axis aberration. An aperture is set between the first and second lenses, and this is of benefit to balance of aberration. The third lens is a negative lens and is provided for correcting off axis aberration. All the lenses can be made of plastics. This facilitates cost reduction, weight reduction, while still maintains a high resolution.

Abstract: A micro lens, from an object side to an image side, sequentially includes a stop, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power. The third and fourth lenses respectively comprise at least one aspherical surface. The negative refractive power gradually decreases from the center to the periphery of the fourth lens, and the refractive power of the periphery of the fourth lens is turned to positive. The relationship of the first lens and the focal length of the micro lens of the micro lens and the relationship of the third lens and the first lens satisfy the desired requirements, thus, to reduce the total length of the micro lens, tolerance sensitivity and cost.

Abstract: A zoom lens system includes, in order from an object side to an image side, a first positive lens group (G1), a second negative lens group (G2), a third positive lens group (G3), and a fourth positive lens group (G4). The second and third lens groups are movable for varying the focal length. The zoom lens system offers a four-times zoom ratio, and employs two plastic aspheric lenses (L3, L9) and a resin hybrid lens (L6). The first lens group consists of two lenses (L1, L2) arranged in an abutting relationship. The second and third lens groups each includes a pair of cemented lenses (L4, L5; L7, L8).

Abstract: A compact imaging lens system includes, in order from the object side to the image side, a first lens (1) of negative refractive power, a free-form surface prism (2) of positive refractive power and a second lens (3) of positive refractive power. The free-form surface prism has an incidence surface (S3), a reflection surface (S4) and an exit surface (S5). The first lens is disposed on the side of the incidence surface, and the second lens is disposed on the side of the exit surface. The free-form surface prism functions equivalent to a right-angle prism with aspheric surfaces.

Abstract: A compact wide-angle imaging lens system includes, in order from the object side to the image side, a first lens (1) of negative refractive power, a free-form surface prism (2) of positive refractive power, a second lens (3) of positive refractive power and a third lens (7) of negative refractive power. The free-form surface prism has an incidence surface (S3), a reflection surface (S4) and an exit surface (S5). The first lens and the free-form surface prism are arranged in a juxtaposed manner, and the second and third lenses are disposed below the free-form surface prism and adjacent to the image side. The free-form surface prism functions equivalent to a right-angle prism with aspheric surfaces.

Abstract: A compact imaging lens system consists of a first positive aspheric lens element (1) on the object side and a second negative aspheric lens element (2) on the image side. The first lens element is a meniscus lens convex toward the image side, whereby the incident light beam can be diverged by the first concave surface (11) of the first lens element, and thus a wide area of the second convex surface (12) of the first lens element can be illuminated by the divergent light beam. The second negative aspheric lens element is provided mainly for correcting chromatic aberration and off-axis aberration.

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

Abstract: A telescope includes an objective lens to receive an optical signal from an object and an electronic signal generator that generates an electronic signal representing for example distance and direction of the object. Both signals travel through a magnification system to from images on a viewer side image plane. The image representing the electronic signal is further transmitted, before reaching the image plane, through a reflector prism, by which the image of the electronic signal is maintained invariable with respect to the variation of magnification factor of the telescope.

Abstract: A compact zoom lens system includes, from the object side to the image side, a negative first lens group (1), a positive second lens group (2), a positive third lens group (3) and a positive fourth lens group (4). The first lens group is stationary, and both the second and third lens groups are movable for effecting focal length change. The fourth lens group is also movable to compensate for image plane shift due to focal length change and thereby maintain the position of the image plane. The compact zoom lens system has a significantly reduced lens count and thus has an overall length of only 20 mm while achieving an approximately 3× zoom ratio. Sufficient back focal length is ensured even for such a short overall length. By employing aspheric lenses (10, 20, 301, 31, 41) for aberration correction, a high level of optical performance can be ensured.