An image capturing lens system includes three lens groups including five lens elements. The three lens groups are, in order from an object side to an image side: first, second and third lens groups. The five lens elements are, in order from the object side to the image side: first, second, third, fourth and fifth lens elements. The first lens element has an object-side surface being convex in a paraxial region thereof. The second lens element has negative refractive power. At least one lens element has an inflection point. A focal length of the image capturing lens system is varied by changing axial distances between the three lens groups in a zooming process. The image capturing lens system has a long-focal-length end and a short-focal-length end. The second lens group is moved relative to the first lens group along an optical axis in the zooming process.

A contactless type optical device includes an image photographing module configured to photograph a subject, the image photographing module including a photographing lens forming an image of light that is scattered from the subject and is incident on the photographing lens; an illuminator configured to radiate illumination light, the illuminator being disposed within a predetermined distance from the image photographing module; a first lens configured to reduce an incidence angle of the illumination light traveling from the illuminator; and a second lens having a first surface to which the illumination light passing through the first lens is incident to be transmitted, and a second surface to which the subject's scattered light scattered from the subject is incident to be transmitted. The photographing lens is disposed such that the subject's scattered light passing through the second lens is incident on the photographing lens.

There is provided herein an optical system for a tip section of a multi-sensor endoscope, the system comprising: a front-pointing camera sensor; a front objective lens system; a side-pointing camera sensor; and a side objective lens system, wherein at least one of said front and side objective lens systems comprises a front and a rear sub-systems separated by a stop diaphragm, said front sub-system comprises, in order from the object side, a first front negative lens and a second front positive lens, said rear sub-system comprises, in order from the object side, a first rear positive lens, an achromatic sub-assembly comprising a second rear positive lens and a third rear negative lens, wherein the following condition is satisfied: f.sub.(first rear positive lens)≤1.8f, where f is the composite focal length of the total lens system and f.sub.(first rear positive lens) is the focal length of said first rear positive lens.

An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having positive refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power. The lenses are arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.

An optical system used in an optical apparatus is configured to include a first lens group having positive refractive power, a focusing group that moves along an optical axis at focusing, and a rear group, in order from an object side, so that the first lens group includes a first-A lens group disposed on the object side of the largest air space A in the first lens group, and that all of the following conditional expressions are satisfied:

1.00<FNo×(TL/f).sup.2<2.50 and 0.30<dA/dG1<0.85

where FNo is the f-number of the optical system focusing on infinity, TL is the total optical length of the optical system focusing on infinity, f is the focal length of the optical system focusing on infinity, dA is the length on the optical axis of the air space A, and dG1 is the length on the optical axis of the first lens group.

A method for designing an optical system for providing reliable, robust and successful realization of a distortion variation function is presented. In a preferred embodiment, the proposed distortion variation optical system includes at least two non-symmetrical elements, which are moving in the transverse direction. The proposed freeform lens contains two transmissive refractive surfaces. The freeform elements designed with this method have preferably a flat surface and a non-symmetrical freeform surface. The two plano-surfaces are preferably made to face each other, so that a miniature camera can be offered. The value of the non-symmetrical freeform surface is used to produce variable optical power when the two freeform elements undergo a relative movement in the vertical direction. Using this method, an optical system with an active distortion, smaller form factor, and better imaging quality can be obtained.

An imaging lens includes an aperture stop and first to fifth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant optical parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.

Wide angle lens for imaging objects disposed away from the optical axis towards the periphery of the field of view.

The present invention relates to a corrective lens for viewing a target located at an extremely short distance from the human eye, for example, a display of a head-mounted display (HMD), (hereinafter, called “a target”), namely, for viewing a target that is located at an extremely short distance of 10 mm 100 mm from the center of the pupil (the ‘extremely short distance’ means a distance of 10 mm˜100 mm in the present invention). The corrective lens for viewing a target located at an extremely short distance has S+18 D˜+50 D; C±0.00 D Ax 0°˜360° to C±6.00 D Ax 0°˜360°; and prismatic power of 0˜8Δ, wherein the corrective lens is provided in front of the display of the head-mounted display (HMD).

An optical imaging system includes a first lens, as second lens, a third lens, a fourth lens, and a fifth lens. The first lens includes a positive refractive power and a convex image-side surface. The second lens includes a positive refractive power, and the third lens includes a negative refractive power. The fourth lens includes a positive refractive power, and the fifth lens includes a positive refractive power. The first to fifth lenses are sequentially disposed from an object side toward an imaging plane.