Abstract: An optical imaging lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens, a second lens, a third lens and a fourth lens. Each of the first lens to the fourth lens has refractive power. A total effective focal length f of the optical imaging lens assembly and an effective focal length f1 of the first lens satisfy: 2.0<f1/f<6.5. A center thickness CT3 of the third lens along the optical axis and an edge thickness ET3 of the third lens satisfy: 2.5<CT3/ET3<4.0.

Abstract: The disclosure provides for a free-space optical communication system that includes a first lens group, a field corrector lens, and a second lens group. The first lens group is configured to receive light received from a remote free-space optical transmitter. The first lens group has a first focal plane. The field corrector lens is positioned between the first lens group and the first focal plane of the first lens group and positioned closer to the first focal plane than the first lens group. The first lens group also is made of material having an index of refraction of at least 2.0, and has a second focal plane. The second lens group is positioned at the second focal plane of the field corrector lens and is configured to couple light to a sensor.

Abstract: A four-piece infrared wavelength lens system includes, in order from the object side to the image side: a first lens element with a positive refractive power, a stop, a second lens element with a refractive power, a third lens element with a positive refractive power, a fourth lens element with a negative refractive power, wherein a focal length of the first lens element and the second lens element combined is f12, a focal length of the third lens element and the fourth lens element combined is f34, and they satisfy the relation: 0.2<f12/f34<1.4. Such a system has a wide field of view, large stop, short length and less distortion.

Abstract: The present invention relates to an optical lens system for a camera comprising in an order from an end at the object side to an end at the image side a first lens having a positive refractive power, a second lens having a positive refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power, wherein the second and third lenses are each designed as meniscus lenses, wherein the surface of the second lens at the object side is convex and the surface of the third lens at the object side is concave. The invention further relates to an imaging system having an image sensor that has a plurality of light-sensitive elements arranged in rows and columns and having such an optical lens system.

Abstract: First, second, third, and fourth lenses (in order from an object side) are arranged between the object and an image sensor where an image of the object is formed. The first lens may have a positive refractive power and may be a meniscus lens that is convex toward the object. The second lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. The third lens may have a positive refractive power and may be a meniscus lens that is convex toward the image sensor. At least one of an incident surface and an exit surface of the fourth lens may be an aspherical surface. The fourth lens may have a negative refractive power or a positive refractive power. A viewing angle ? of the lens optical system may satisfy a conditional expression, 2.5<|tan ?|<3.5.

Abstract: An optical unit and an image pickup unit are provided that allow a full angular field to be increased in spite of small size and low cost. An image pickup lens 100 has a first lens 111 with a positive power, a second lens 113 with a positive power, a third lens 114 with a positive power, and a fourth lens 115 with a negative power that are arranged in order from an object side OBJS toward an image surface side, that are arranged in order from the object side toward the image surface side.

Abstract: An optical device is to be disposed between a test screen and a test camera that captures an image on the test screen through the optical device. The optical device includes first, second, third and fourth lenses arranged from a camera side to a screen side in the given order. The first lens has a shape factor ranging from ?10 to 5, the second lens is a positive lens and has a shape factor ranging from ?15 to 2, the third lens is a positive lens and has a shape factor ranging from ?30 to 1, and the fourth lens is a positive lens and has a shape factor ranging from ?30 to 1. A ratio of a focal length of the optical device to that of the test camera ranges from 1 to 80.

Abstract: A four element lens system for use with an imaging sensor includes first, second, third, and fourth lens elements and an optical filter that are arranged sequentially in order from an object side to an imaging side. The lens elements are coated with an anti-reflective film. The lens system further includes an optical filter that is disposed at a distance from the imaging sensor. The lens elements are relatively positioned to each other to satisfy specific conditions. The lens elements further include thickness to diameters ratios that satisfy specific conditions.

Abstract: An optical device is to be disposed between a test screen and a test camera that captures an image on the test screen through the optical device. The optical device includes first, second, third and fourth lenses arranged from a camera side to a screen side in the given order. The first lens has a shape factor ranging from ?10 to 5, the second lens is a positive lens and has a shape factor ranging from ?15 to 2, the third lens is a positive lens and has a shape factor ranging from ?30 to 1, and the fourth lens is a positive lens and has a shape factor ranging from ?30 to 1. A ratio of a focal length of the optical device to that of the test camera ranges from 1 to 80.

Abstract: An imaging lens includes four lenses arranged in order from the object side to the image side: an aperture stop, positive (refractive power) first lens having a convex object-side surface near the optical axis, second lens having a positive meniscus shape near the axis, positive third lens having a convex image-side surface near the axis, and negative fourth lens having a concave image-side surface near the axis. All lens surfaces are aspheric. The image-side aspheric surface of the fourth lens has a pole-change point off the optical axis and conditional expressions (1) and (2) are satisfied: 0.75<TLA/(2IH)<0.90??(1) 0.90<TLA/f<1.

Abstract: An optical unit and an image pickup unit are provided that allow a full angular field to be increased in spite of small size and low cost. An image pickup lens 100 has a first lens 111 with a positive power, a second lens 113 with a positive power, a third lens 114 with a positive power, and a fourth lens 115 with a negative power that are arranged in order from an object side OBJS toward an image surface side, that are arranged in order from the object side toward the image surface side.

Abstract: The wide-angle imaging lens module includes four lenses arranged from an object side to an image side in a sequence of: the first lens, having a positive refractive power, a convex surface on the object side and at least one aspheric surface; a diaphragm; the second lens, having a positive refractive power, a concave surface on the object side and at least one aspheric surface; the third lens, having a positive refractive power, a concave surface on the object side and at least one aspheric surface; the fourth lens, having a negative refractive power, a convex surface on the object side and at least one aspheric surface. The first and the second lenses perform a symmetry concave, providing the wider field of view angle and the larger aperture. A structural design that allows lenses to restrain better aberrations performances of aspheric surfaces further provides high-definition and high imaging qualities.

Abstract: An optical lens assembly for image photographing, in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element with positive refractive power; a third lens element with positive refractive power having a convex image-side surface; a plastic fourth lens element with negative refractive power having a concave image-side surface, both object-side and image-side surfaces being aspheric, and having at least one inflection point. Additionally, the optical lens assembly for photographing image has an image sensor on the image plane for imaging a photographed object and satisfies specific conditions. Thereby, this invention has a high resolving power and can shorten the total length of the lens assembly for using in camera and mobile phone camera with well photographing abilities.

Abstract: An optical lens assembly for image photographing, in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element with positive refractive power; a third lens element with positive refractive power having a convex image-side surface; a plastic fourth lens element with negative refractive power having a concave image-side surface, both object-side and image-side surfaces being aspheric, and having at least one inflection point. Additionally, the optical lens assembly for photographing image has an image sensor on the image plane for imaging a photographed object and satisfies specific conditions. Thereby, this invention has a high resolving power and can shorten the total length of the lens assembly for using in camera and mobile phone camera with well photographing abilities.

Abstract: A disclosed projection optical system for projecting and forming an enlarged image of an image displayed in a planar manner as an object includes: a lens system including, from an object side, at least a lens group providing telecentricity to an object space side, a lens group controlling divergence of angles of view, a diaphragm, a lens group converging the angles of view, and a lens group converging and subsequently enlarging the angles of view; and a catoptric system disposed on an image side relative to the lens system and including a mirror having negative power. Each lens group of the lens system and the mirror having negative power share an optical axis and the optical axis is shifted relative to a center of an object surface.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B–1F and FIGS. 8B–8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B–1F and FIGS. 8B–8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: A single focus lens is disclosed that is formed of only four lens elements. In order from the object side, these are: a first lens element of positive refractive power and having either a concave surface or planar surface on the object side; a second lens element of weak refractive power and meniscus shape that is made of plastic with at least one surface aspheric; a third lens element which has positive refractive power and a convex surface on the image side; and a fourth lens element of weak refractive power and meniscus shape that is made of plastic with at least one surface aspheric and with its concave surface on the image side. Preferably, various conditions are satisfied in order that the single focus lens be compact and favorably correct aberrations so as to provide a high quality image.

Abstract: Projection lens systems for use with cathode ray tube (CRT) projection televisions are provided which have positive first lens units (U1) and negative second lens units (U2) where the negative second lens units are customized in terms of at least one optical property for at least two of the colors of light produced by the CRTs with which the units are used. The at least one optical property is not spectral transmission, although the second lens units can also be customized for spectral transmission. As illustrated in FIGS. 1B-1F and FIGS. 8B-8F, such customization of a non-transmissive property provides an effective and cost effective approach for improving the color performance of CRT projection lens systems. Constructions for the positive first lens unit which improve image contrast and reduce manufacturing costs are also provided.

Abstract: A zoom lens of the negative lead type includes, in order from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, a third lens unit of negative refractive power consisting of one negative lens, and a fourth lens unit of positive refractive power consisting of one positive lens, wherein, during zooming from the wide-angle end to the telephoto end, all the lens units move along an optical axis in such a manner that the separation between the first lens unit and the second lens unit decreases, the separation between the second lens unit and the third lens unit increases and the separation between the third lens unit and the fourth lens unit decreases.

Abstract: A zoom lens focusing system for and method of focusing from an infinite to a close distance. The system includes a zoom lens comprising a plurality of lens groups each being axially movable to define a plurality of positional states and focal length for each positional state. Each of the plurality of lens groups moves for focusing such that the ratios of movement amounts of the respective lens groups vary as a function of the focal length. The method includes the steps of providing the above-described zoom lens, and then focusing by moving the plurality of lens groups such that the ratios of movement amounts of the respective lens groups vary as a function of the focal length. The focusing system and method each preferably satisfy a number of conditions.

Abstract: An eyepiece lens has an apparent field of no less than 40.degree., and minimizes eye relief error. The eye relief includes a distance between a lens surface closest to an eye point side in the eyepiece lens and an eye point. The eyepiece lens comprises an assembly of lens groups including, from the eye point, a first lens group G.sub.1 that includes one positive lens component, a second lens group G.sub.2 with positive refracting power that includes a cemented lens having a negative lens component and a positive lens component, a third lens group G.sub.3 with positive refracting power that includes a cemented lens having a positive lens component and a negative lens component, and a fourth lens group G.sub.4 that includes one negative lens component. The assembly of lenses is configured such that 1.4.ltoreq..vertline.R7/R4.vertline.

Abstract: A wide-angle variable focal length lens system comprising a first lens unit which is to be kept stationary for varying a focal length of the variable focal lens system and composed of a single positive lens component, a second lens unit which comprises at least one positive lens component and has a negative refractive power as a whole, a stop, and a third lens unit having a positive refractive power; and configured so as to perform variation of a focal length of the lens system and adjustment of an image location by moving the second lens unit and the third lens unit along an optical axis in directions which are opposite to each other. This variable focal length lens system has a field angle of 64.degree. to 74.degree. at a wide position thereof, a variable focal length ratio of 3 to 3.3 and an F number on the order of 2, and comprises a small number of lens components.

Abstract: A taking lens for an underwater camera is constituted in the order from the side of a subject of a first lens group having no or slight refracting power, a second lens group having a positive refracting power, a third lens group having positive refracting power and a fourth lens group having negative refracting power. When focusing from the infinity to a closer distance, the first lens group is fixed to the image surface and the second and third lens groups are moved forward along the optical axis such that the distance between the second and third lens groups is changed.

Abstract: A projecting lens for projecting the image of an object onto a screen comprising, in the order from the screen side, a first lens group of a positive refractive power; a cemented second lens group of a positive refractive power; a third lens group of a negative refractive power; and a fourth lens group of a positive refractive power with a concave surface at the screen side; wherein each of the first and third lens group has at least an aspherical face, and the focal length f of the projecting lens, the focal length f1 of the first lens group and the focal length f3 of the third lens group satisfy conditions: 0<f/f1<0.25 and -0.1<f/f3<0.