Tokyo Electric Co.

Tokyo Kogaku Kikai Kabushiki Kaisha

Tokyo Kogaku Kikai Kabushiki

Yasuo Iwafune

Yasuo Matsumoto

Tomonori Ikumi

Kazunori Murakami

Yuji Kobayashi

Hideo Iwai

A postobjective optical deflector comprising: a polygonal optical deflector (polygonal rotating mirror) having a plurality of convex reflecting surfaces each being curved surface other than a spherical surface or a portion of a cylindrical surface; and a pseudocylindrical lens disposed between the polygonal optical deflector and an objective surface, having a cylindrical surface having its power in the feed direction or a rotationally symmetric surface rotationally symmetric with respect to an axis of rotational symmetry parallel to the scanning direction, and a curved surface represented by a polynomical of even degree and having its power in the scanning direction. The combined performance of the correcting effects of the polygonal optical deflector and the pseudocylindrical lens corrects the curvature of image surfaces and f.theta. characteristics at a high accuracy.

Postobjective optical deflector

An optical scanning system is constructed in a compact construction by attaching a light deflecting member to one end of the output shaft of a motor internally having a space for containing parts, forming an optical path extending through the space in the output shaft of the motor between a semiconductor laser and the light deflecting member, and providing at least a collimator lens in the space for containing parts. A meniscus lens, i.e., a correcting optical system, having a concave surface of a radius of curvature in the range of 8 to 20 mm is disposed with its concave surface facing the light deflecting member so that the distance between the reflecting point on the light deflecting member and the optical center of the concave surface is in the range of 5 to 10 mm to limit the curvatures of image field with respect to the scanning direction and with respect to the feed direction of the scanning light beam are limited to a very small degree. Thus, the optical scanning system has a simple, compact construction.

Optical scanning system

A postobjective optical scanner comprising a polygonal optical deflector having a plurality of reflecting surfaces each being a curved surface varying in curvature from position to position thereon; and a correcting lens disposed between the polygonal optical deflector and the objective surface on an optical path, and having a rotationally symmetric curved surface of incidence having a cross section having the shape of an arc of a circle with its center on the axis of rotational symmetry, rotationally symmetric with respect to a plane including the axis of rotation of the polygonal optical deflector and perpendicular to the axis of rotational symmetry and having its power in both the feed direction and the scanning direction, and a surface of departure symmetrical with respect to a plane perpendicular to the scanning direction and having its power in the scanning direction. The combined performance of the correcting effects of the polygonal optical deflector and the correcting lens corrects the curvature of image surfaces and f-.theta. characteristics at a high accuracy.

Postobjective optical scanner

A postobjective optical scanner comprising a polygonal optical deflector (polygonal rotating mirror) having a plurality of convex reflecting surfaces each being a curved surface other than a spherical surface or a portion of a cylindrical surface. The deflector also utilizes a pseudocylindrical lens disposed between the polygonal optical deflector and an objective surface, having a cylindrical surface having its power in the feed direction or a rotationally symmetric surface rotationally symmetric with respect to an axis of rotational symmetry parallel to the scanning direction, and a curved surface represented by a polynominal of even degree and having its power in the scanning direction. The combined performance of the correcting effects of the polygonal optical deflector and the pseudocylindrical lens corrects the curvature of image surfaces and f.theta. characteristics at a high accuracy.

A polygon mirror has a plurality of elliptically-curved convex mirror surfaces functioning as light reflection surfaces, each having substantially the same shape as the maximum curvature portion of an ellipse which has long axis b and short axis c. The convex mirror surfaces are uniformly arranged on the circumference of an inscribed circle whose center is set on the long axis b, whose radius is Rm, and which is in contact with the maximum curvature portion of the ellipse. The polygon mirror reflects an incident light beam while being rotated, and scans the incident light beam in the range of effective scanning length Lo on a preset scanning plane which is set at incident light beam travelling distance R from the center of the inscribed circle of the polygon mirror.

Polygon mirror

A level measuring instrument including a staff having a plurality of light emitting diodes located along the length of the staff with predetermined spacings. The light emitting diodes produces coded lights which are distinguishable with each other. The instrument further includes a light receiving optical system and an electrical system which discriminates a particular diode which has produced the light as received by the optical system.

Level measuring instrument having a staff with light-emitting elements

An angle measuring instrument such as a theodolite having a housing containing a viewing optical system. The housing has a pair of axially aligned horizontal shafts through which it is mounted on a support frame for a swingable movement in a vertical plane. The shafts are mounted on the frame through ball bearings having inner and outer races. One of the inner and outer races is preloaded in the axial direction so that a stable movement of the bearing is ensured.

Bearing means for angle measuring instruments

A base board device for detachably mounting a measuring instrument such as a transit. The base board device has a centering telescope for locating the base board directly above a point on the ground. The centering telescope has a mark in the eyepiece which defines a viewing axis directed vertically downwardly. In order to determine whether or not the viewing axis as defined by the mark is directed accurately downwardly, the centering telescope is used. To facilitate that use, the base board is formed at the center thereof with an aperture so as to make it possible to observe the vertically downward point through the centering telescope.

Growing community of inventors

Tokyo, Japan

Yasuo Iwafune