Abstract: A zoom lens comprises, from front to rear, a first lens unit of positive power and a second lens unit of negative power with the limitation of the total number of lens elements to 4 or less, the first and second lens units axially moving in differential relation to effect zooming. By properly setting the refractive power arrangement of all the lens units and the spacings between the lens elements and by introducing an aspheric surface, the zoom lens is well corrected for high optical performance, although the total number of lens elements is few.

Abstract: A laser beam is projected through the optical system of an endoscope and scanned in raster fashion by means of a scanning head at a proximal end of the endoscope tube. The beam is projected from a distal end of the endoscope tube so as to be scanned over an object. Light reflected from the object is detected and used to form a television image. The range of the object is measurable in a ranging mode of the apparatus in which the depth of focus of the projected laser beam is reduced using a zoom lens at the distal end of the endoscope and the focus distance of the projected beam varied until an in-focus position is detected by analysis of the reflected light. Detection of the in-focus position relies on characteristics of laser speckle, a selected portion of the object being scanned in ranging mode to detect maximum modulation in the speckle pattern which occurs when the focus distance corresponds to the range of the object.

Abstract: A zoom lens system comprises from the object side, a front lens group having a refractive power of a predetermined sign and a rear lens group having a refractive power of different sign from that of the front lens group. The front lens group is shiftable along the optical axis of the lens system in a zooming operation, and movable perpendicularly to the optical axis for decreasing a blur caused by a hand shake. The rear lens group is shiftable along the optical axis in the zooming operation.

Abstract: In a zoom lens system for use with a compact camera having a wide coverage of angles that comprises, in order from the object side, a first lens group having a positive focal length and which performs zooming by changing the distance beween the first and second lens groups, the said first lens group comprises, in order from the object side, a front subgroup 1F having a positive focal length, a diaphragm stop and a positive rear subgroup 1R with a small power, and the first lens in the front subgroup 1F is a negative lens, with the specific conditions.

Abstract: A zoom lens system for use with a compact camera is disclosed which has a wide coverage of angles and which comprises, in order from the object side, a first lens group having a positive focal length and a second lens group having a negative focal length and which performs zooming by changing the distance between the first and second lens group. The first lens group comprises, in order form the object side, a subgroup 1a having a negative focal length and a subgroup 1b having a positive focal length. The subgroup 1a is composed of at least two lens elements including a negative first lens element on the object side and a meniscus lens element on the image side which has a concave surface directed toward the object with a large curvature and a convex surface directed toward the image with a large curvature. The subgroup 1a further satisfies the following condition:-0.5<f.sub.1G /f.sub.1 .ltoreq.0 (1)wheref.sub.1G : the focal length of the first lens group; andf.sub.

Abstract: A zoom lens system comprising, in order from the object side, a first lens group that includes at least three lens elements and that has a negative overall power and a second lens group that includes at least four lens elements, with the negative lens element of the greatest powre being cemented to the adjacent positive lens element, and that has a positive overall power. The zoom lens system is capable of changing its focal length by adjusting the distance between the first and second lens groups. The zoom lens system satisfies the specific conditions.

Abstract: A compact-size, light-weight, low-cost zoom lens system with high optical quality is achieved by using a ray restrictor placed at the most object side of the zoom lens system. In one type, the ray resistor shifts toward the object at a speed different from that of the most object side lens of the zoom lens system as the zoom lens system is zoomed toward the longest focal length, which effectively blocks harmful rays causing coma flare in the peripheral area. In another type, the aperture diameter of the ray restrictor varies according to a zooming operation. The ray restrictor of any type is especially effective when used in a zoom lens system composed of two lens groups. By introducing one or more aspherical surfaces satisfying a certain condition (or conditions) in the zoom lens system, various aberrations are further favorably corrected.

Abstract: A compact wide angle zoom lens has a view angle as wide as 65.degree.-72.degree. and a magnification varied by changing an inter-group spacing. The zoom lens comprises a first lens group having a positive refractive power and a second lens group having a negative refractive power. The first lens group, sequentially from an object, includes a front group having a positive refractive power and a rear group having a positive refractive power. The front group includes a meniscus first lens component having a positive refractive power, a second lens component with its more intensive concave surface directed to the object, having a negative refractive power, a third lens component having a positive or negative refractive power, and a fourth lens component having a positive refractive power. The rear group includes a fifth lens component having a positive refractive power.

Abstract: In a compact wide-angle zoom lens which has, in succession from the object side, a first lens unit of positive refractive power and a second lens unit of negative refractive power and in which a magnification change is effected by the relative unit spacing between the two lens units being varied, the first lens unit has at least two negative lens components and at least one positive lens component, and one of the at least two negative lens components is disposed most adjacent to the object side of the first lens unit, and has a negative meniscus shape having its convex surface facing the object side.

Abstract: A zoom lens system comprising a front lens unit which is composed of a positive meniscus lens component having a convex surface on the object side, a negative lens component and at least one positive lens component, and has a positive refractive power as a whole, and a rear lens unit which is composed of a positive lens component, a biconcave lens component and a negative meniscus lens component having a convex surface on the image side, and has a negative refractive power as a whole; and adapted so as to perform variation of focal length by varying the airspace reserved between said front lens unit and said rear lens unit.

Abstract: An objective optical system for endoscopes consisting, in the order from the object side, of a front lens unit having negative refractive power, an aperture stop and a rear lens unit having positive refractive power and comprising at least one aspherical surface in each of the lens units. This objective optical system for endoscopes has distortion of a small absolute value, a distortion curve of natural shape, favorably corrected aberrations, and is composed of lens elements easily manufacturable.

Abstract: A compound zoom lens optical system includes a variable focal length photographing lens consisting of a first lens group having a positive refracting power, and a second lens group having a negative refracting power from an object side in turn. A conversion lens is separably added to an image side of the variable focal length photographing lens. The conversion lens is simultaneously movable along an optical axis to be interlocked with at least one of the first and second lens groups of the variable focal length photographing lens so as to change a synthesized focal length with said variable focal length photographing lens. The variable focal length photographing lens and the conversion lens satisfy the following conditions:-1.5<.PHI..sub.1 /.PHI..sub.2 <-0.8-1.1<.PHI..sub.1 /.PHI..sub.23 <-0.2where .PHI..sub.1 is the refracting power of the first lens group, .PHI..sub.2 is the refracting power of the second lens group, and .PHI..sub.

Abstract: A small type zoom lens composed of 3 to 5 lenses, which is suitable for a compact camera. The lens has a telephoto type optical arrangement including a positive first lens unit and a negative second lens unit, both of the lens units being moved forward as a whole while narrowing a space therebetween during variation of power from a short focal end to a long focal end. The first lens unit has an arrangement of refracting powers substantially symmetrical with respect to a diaphragm to correct aberrations produced by the second lens unit composed of a negative single lens.

Abstract: The invention is directed to an IR-pancratic optical device which includes a drive for displacing optical members thereof. The drive permits the focal length range to be passed through in 0.5 second. The drive includes a rotatably mounted drum on which a steel band is attached. Redirecting roller guides are provided to enable the rotational movement to be translated into a linear movement. The IR-pancratic optical device includes forward and rearward optical members and two intermediate optical members are arranged therebetween. One of the intermediate optical members is attached to the band and is moved along the optical axis. A cam control couples the movement of the second intermediate optical member to the movement of the first intermediate optical member.