Nippon Sheet Glass Company, Limited

Minoru Toyama

Hisami Nishi

Shigeo Kittaka

Shuya Ogi

Koichiro Iki

Hiroyuki Ichikawa

Hiroshi Ueno

Tomitaka Takagi

Hiroshi Koshi

Yoshikazu Kaite

Noboru Akazawa

Atsushi Akiba

An optical imaging system is provided that includes a rod lens array and has the optimum refractive index distribution for achieving a high resolving power. The refractive index distribution of rod lenses can be expressed by()&#xb7;{1&#x2212;()&#xb7;()19 ()&#xb7;()}Eq. 45where r is a radial distance from the optical axis of the rod lenses, nis a refractive index on the optical axis of the rod lenses, and g, h, hand hare refractive index distribution coefficients. The refractive index distribution coefficients h, hand hare set on a spheroid in a Cartesian coordinate system with hbeing x-axis, hbeing y-axis and hbeing z-axis. The spheroid is defined by a vector X* that is expressed by()=Eq. 46where O* is a vector from the origin of the Cartesian coordinate system to the center of the spheroid, A*, B* and C* are vectors in the directions of the major axis, the mean axis and the minor axis of the spheroid, respectively, and k, kand ksatisfy k+k+k&#x2266;1.

Optical imaging system with rod lens array

An optical write-in head for obtaining a clear image even in printing at a relatively high recording density without generating strip-like irregularities in most cases. The optical write-in head applies light carrying image information to a photosensitive substance. The optical write-in head includes an array light source having a plurality of dot light sources, each of which selectively emits the light corresponding to the image information, and a lens array facing the array light source. The lens array has a plurality of lens elements which corresponds to the plurality of dot light sources respectively. An angular aperture &#x3b8; of each of the lens elements is set in a range of about 14&#xb0; to 18&#xb0;.

Optical write-in head, image forming apparatus using the same, and method for inspecting the apparatus

An image transfer device having: a lens array laminateforming an erecting unit magnification optical system, the lens array laminate including a plurality of lens array sheetsof the same specification each of which has convex-convex lens elementsarranged in a plurality of rows and which are substantially closely laminated in a direction of each lens optical axis. Typically, two to four lens array sheets of the same specification each of which has convex-convex lens elements each having are fractive index of not lower than 1.45 and arranged in 3 to 9 rows are closely laminated on each other or one another in a direction of each lens optical axis. Each of the lens array sheets is preferably formed so that the lens thickness is in a range of from about 4 mm to about 0.5 mm and the number of lens rows is in a range of from 4 to 6.

Image transfer device having laminated lens array sheets

A light source-optical fiber coupler using a gradient index rod lens by which a diffused luminous flux emitted from a light source (for example, a semiconductor laser ) is coupled onto an end surface of an optical fiber (for example, a single-mode optical fiber ). The gradient index rod lens has a planar end surface facing the light source, and a convex spherical end surface facing the optical fiber. The gradient index rod lens has a light source side numerical aperture NA in a range of from 0.40 to 0.75, an effective lens radius r in a range of from 0.3 to 1.0 mm, and a spherical curvature radius R in a range of from 1.2 to 2.0 mm.

Light source-optical fiber coupler

Rod lens array for line scanning

In an image forming apparatus, an object surface ( ) is disposed facing one end face of a rod lens array ( ), while an image surface ( ) is disposed facing the other end face thereof. A lens working distance of the rod lens array on the object side is substantially equal to that on the image side. An actual object-image distance Tco is set between the conjugate length TC1 at which the average value MTFave of the MTF of the rod lens array in the lens array direction is maximized and the conjugate length TC2 at which the &Dgr;MTF(&equals;(MTFmax&minus;MTFmin)/MTFave) is minimized, and a shift quantity &Dgr;TC(&equals;&verbar;TCo&minus;TC1&verbar;) is set within 0 mm<&Dgr;TC<&plus;02 mm for the conjugate length TC1 at which the MTFave is maximized.

Image forming apparatus

An imaging optical element is comprised of a gradient index rod lens of which external peripheral surface is a smooth surface without being processed by means of a flare-cut treatment and a field limitation stop member mounted on the lens surface at the incidence side thereof. As for the stop member, the length t thereof is: t>1 &middot;D/2X (where, 1 : a lens working distance, D: a rod lens diameter, X: a radius of field of view), whereby the angle of incidence of beam &thgr; at the center of the lens satisfies &thgr;<tan (X/1 ) . It is effective especially when an application thereof is made to a rod lens array comprised of a plurality of rod lenses arranged into an array.

Imaging optical element

An imaging optical apparatus comprising a gradient-index rod lens array and two transparent or light transmitting optical elements that are substantially identical in shape and imaging characteristics and which are provided in the object space and the image space in the optical path of said gradient-index rod lens array in such a way that they are symmetrical with respect to said gradient-index rod lens array.

Imaging optical apparatus

An optical imaging system includes a rod lens array, whose individual lenses have a refractive index distribution optimized for high resolving power, which can be expressed by

Optical imaging system

This invention relates to a method of performing an ion exchange of optical glass to produce an axial gradient index material having a good linear distributiion by bringing a glass body containing a monovalent cation component into contact with a medium containing a monovalent cation component and exchanging these cation components under a predetermined condition.

Method of performing an ion exchange of optical glass

An optical coupler comprises a lens for coupling a light source and an optical fiber wherein the lens comprises a transparent column in which a refractive index n(r) at a distance r from an optical axis is expressed by n.sup.2 (r)=n.sub.0.sup.2 {1-(gr).sup.2 +h.sub.4 (gr).sup.4 +h.sub.6 (gr).sup.6 +h.sub.8 (gr).sup.8 + . . . }, and satisfies the following conditions when Sf=g/0.3:

Optical coupler

A collimator lens to be used for an optical recording/reproducing apparatus is constituted by a refractive index distribution type lens to satisfy specific conditions, thereby the invention provides the collimator lens which is good in the productivity and has the wave surface aberration being equivalent to or better than that of a collimator lens using a spherical lens.

Collimator lens

A collimator lens of graded index type for a semiconductor laser which can be manufactured at low cost and has the residual wavefront aberration equal to or less than that of a conventional collimator lens of spherical lens system is provided by comprising a rod lens of graded index type made of a cylindrical transparent medium having the refractive index n(r) at position of radial distance r from the central axis represented by;

In a lens for an optical recording/reproducing apparatus of the invention, a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by:

Lens for an optical recording/reproducing apparatus and optical

An element of the invention focuses and projects a parallel or substantially parallel light beam onto an optical information recording medium. The element consists of a transparent columnar body having a convex surface as the input surface and a flat surface as the output surface.

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Osaka, Japan

Minoru Toyama