Abstract: A method for collating independent figure elements in an object image with a reference image both including independent elements which are not interlinked with each other. The method comprises steps of defining a relative coordinate system in an image plane for the reference image and the object image on the basis of centers of gravity of two distinctive independent elements which are identified with values indicative of features of the elements; and collating pairs of independent elements between the reference image and the object image on the basis of the relative coordinate system.

Abstract: A graded-index lens for focusing an erect unmagnified image out of the lens has a refractive index varying radially in a cross-sectional plane normal to the optical axis thereof. The graded-index lens comprises a cylindrical medium whose refractive index at a radial distance r from an optical axis within a cross-sectional plane normal to the optical axis, is expressed by:n.sup.2 (r)=n.sub.0.sup.2 [1-(gr).sup.2 +h.sub.4 (gr).sup.4 ]where n.sub.0 is the refractive index on the optical axis, g is a parameter indicating the gradient of the varying refractive index, and h.sub.4 is a fourth-order refractive index distribution coefficient, the fourth-order refractive index distribution coefficient h.sub.4 being in the range of:0.6<h.sub.4 <1.0.

Abstract: In an image correlation calculation apparatus for optically calculating correlations between reference patterns and an image such as a character or any other figure, the image such as the character or any other figure subjected to correlation calculations is optically multiplied by a multiplier to form simultaneously in parallel a plurality of optical pattern images of a substantially identical shape, and optical correlation calculation between the plurality of optical pattern images and the reference patterns formed on various types of reference masks is performed individually and instantaneously, the various type of reference masks being arranged at a position spaced apart by a predetermined distance from the plurality of optical pattern image, thereby detecting beams emitted through the various types of reference masks.

Abstract: A reference beam type optical laser Doppler velocimeter for emitting two or more probe beams to an object to be measured at a predetermined angle to multi-dimensionally measure a velocity and/or a displacement vector of the object due to Doppler shifts of beams reflected by the object. This velocimeter includes a frequency shifting means for dividing a laser beam from a single light source into two or more beams, and shifting optical frequencies of the beams each by a predetermined shift amount, a photodetecting means for receiving the reflected and reference beams to obtain a detection current, and a bandpass filter for causing the detection current to pass therethrough to obtain a required signal.

Abstract: In an image recognition apparatus for identifying an input image such as a character, any other graphic pattern or the like by comparing the input image with a plurality of reference image, an optical image recognition means simultaneously performs image information detection processing of a plurality of optical pattern images of substantially an identical shape obtained by multiplying the input image, thereby detecting a plurality of image information data corresponding to the plurality of optical pattern images and hence identifies the input image. When the input image cannot be identified by the optical image recognition means, an electronic image recognition means performs digital correlation calculations for limited ones of the reference images according to the above image information data. Therefore, image recognition can be performed by an inexpensive apparatus at high speed, and a high throughput can be obtained. In addition, a high recognition rate can be obtained.

Abstract: In a lines and character separation apparatus for separating lines and characters in a document page, the separation being a step in pattern recognition, images are multiplied from one area within the page, a plurality of photosensor arrays are used which have different alignment directions of pluralities of light-receiving elements thereof and which are respectively paired with the multiple images, and the lines and the characters can be separated at high speed.

Abstract: In a page segmentor for dividing a page into areas each having a single feature, the division being performed as preprocessing for pattern recognition, one of the areas within the page is multiplied into multiple images, a feature of each area is extracted according to the presence or absence of each of pairs between the multiple images and a plurality of different masks, and the page is divided into areas until each area has a single feature. High-speed page segmentation can be achieved so as to obtain a desired feature.

Abstract: In an apparatus for preprocessing of character recognition so as to obtain data necessary for character recognition, page segmentation is performed by simultaneously extracting a plurality of features, separation between lines, separation between characters, and separation between the lines and the characters are simultaneously performed, and a calculation time for normalizing the separated individual characters can be reduced, thereby performing proprocessing required for character recognition systematically at high speed.

Abstract: 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/0.3:0<C.sub.1 /Sf<0.67C.sub.2 =00.ltoreq.l.sub.1 .multidot.Sf.ltoreq.1.50.5.ltoreq.h.sub.4 .ltoreq.2.0wherein C.sub.1 and C.sub.2 are curvatures of input and output end faces (the sign is positive when the center of the radius of curvature is positioned at the side of the optical fiber with respect to the end face), l.sub.1 is a back focus at the side of the light source, n.sub.0 is a refractive index on the optical axis, and g, h.sub.4, h.sub.6 and h.sub.8 are distribution constants.

Abstract: 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:n.sup.2 (r)=n.sub.O.sup.2 {1-(g.multidot.r).sup.2 +h.sub.4 (g.multidot.r).sup.4 +h.sub.6 (g.multidot.r).sup.6 +h.sub.8 (g.multidot.r).sup.8 + . . . }and the following conditions are satisfied:R.sub.2 =.infin.3.0.gtoreq.R.sub.1 /(1+0.75S).gtoreq.0.81.40.ltoreq.n.sub.O .ltoreq.1.87-0.6g.multidot.S0.75.gtoreq.g.multidot.f.gtoreq.0.45wheren.sub.O : refractive index on the optical axisg, h.sub.4, h.sub.6, h.sub.8 : coefficientsR.sub.1 : radius of curvature of a first surfaceR.sub.2 : radius of curvature of a second surfaceS: working distancef: focal distance of an overall optical system at an image side.An optical recording/reproducing apparatus of the invention has a lens as described above as an objective lens.

Abstract: 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;n.sup.2 (r)=n.sub.o.sup.2 }1-(g.multidot.r).sup.2 +h.sub.4 (g.multidot.r).sup.4 +h.sub.6 (g.multidot.r).sup.6 +h.sub.8 (g.multidot.r).sup.8 +. . . }and satisfying following conditions:(1) r.sub.1 =.infin.;(2) r.sub.2 =.infin.;(3) 6.70 mm.ltoreq.Z+fB.ltoreq.7.30 mm;(4) 1.60.ltoreq.n.sub.0 .ltoreq.1.65;(5) 0.18 mm.sup.-1 .ltoreq.g.ltoreq.0.22 mm.sup.-1 ;(6) 0.38 .ltoreq.h.sub.4 .ltoreq.0.87;(7) .vertline.h.sub.6 .vertline.<5; and(8) 0.21.ltoreq.NA.ltoreq.0.24;where r.sub.1 and r.sub.

Abstract: 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.